0003+380 : The redshift was derived from several spectra taken by one of us (H.K.) with the Steward Observatory 90" telescope. 0010+405 : The new classification as a galaxy as well as its redshift is given in Stickel & Kuehr (1993a). The redshift has previously been listed by Biermann et al. (1987), based on spectra taken by one of us (H.K.) with the Steward Observatory 90" telescope. 0022+390 : The redshift was derived from several spectra taken by one of us (H.K.) with the Steward Observatory 90" telescope. The redshift has also been measured by Xu et al. (1993). 0024+348 : The optical spectrum and redshift are given in Stickel & Kuehr (1993b). 0026+346 : The classification as a galaxy as well as the optical magnitude was derived from an R - band CCD image taken with the 3.5m telescope on Calar Alto, Spain in September 1989. The image confirms the classification given by Prestage & Peacock (1983), while the classification as a QSO by Rieke et al. (1979) is rejected. 0035+413 : The optical spectrum and redshift are given in Stickel & Kuehr (1993b). 0040+517 : The redshift has been taken from Lawrence et al. (1986). The redshift listed by Spinrad et al. (1985) and Wall & Peacock (1985) is incorrect. 0102+480 : The tentative classification as an optical blank field is due to Kuehr (1977a). 0108+388 : The identification, magnitude, and redshift were taken from O'Dea et al. (1991). 0110+495 : The redshift is derived from a single broad emission line identified with Mg II 2798, which was detected in a spectrum taken by one of us (H.K.) with the Multiple Mirror Telescope. 0218+357 : The redshift of the intervening absorption line system has been measured by Stickel & Kuehr (1993b) and Browne et al. (1993). The optical magnitude is given in Stickel & Kuehr (1993b). This source is most likely a gravitational lens system (O'Dea et al. 1992, Patnaik et al. 1993, Browne et al. 1993). 0223+341 : The identification and magnitude have been taken from Peacock et al. (1981). 0246+428 : The optical spectrum and redshift are given in Stickel & Kuehr (1993b). 0247+467 : The optical magnitude has been taken from Condon et al. (1991). A redshift estimate based on the optical magnitude is listed by Vigotti et al. (1989), but has not been included in Table 1. 0309+390 : This radio source is incorrectly associated with NGC 1233 (UGC 2586) in Burbidge & Crowne (1979) and Hewitt & Burbidge (1991). 0327+408 : The optical spectrum and redshift are given in Stickel & Kuehr (1993b). 0344+405 : The identification and magnitude were taken from Willson (1972). The optical spectrum and redshift are given in Stickel & Kuehr (1993a). 0402+379 : The identification and magnitude were taken from Wills et al. (1973). The optical spectrum and redshift are given in Stickel et al. (1993a). The redshift has also been measured by Xu et al. (1993). 0444+634 : The magnitude, optical spectrum, and redshift are given in Stickel & Kuehr (1993b). 0537+531 : The identification and optical magnitude have been taken from Kuehr (1977a). The redshift is derived from a spectrum taken by one of us (H.K.) with the Multiple Mirror Telescope. 0602+673 : The identification and magnitude have been taken from Meisenheimer & Roeser (1983). 0620+389 : The identification and optical magnitude have been taken from Kuehr (1977a). The redshift is given by Xu et al. (1993). 0646+600 : The identification and optical magnitude were taken from Meisenheimer & Roeser (1983). The optical spectrum and redshift are given in Stickel & Kuehr (1993b). 0647+693 : The optical magnitude and redshift have been taken from Owen & White (1991) and Owen et al. (1988), respectively. The radio flux S_{5GHz} and radio spectral index alpha_{11-6} has been taken from Andernach et al. (1988). 0657+687 : The optical spectrum and redshift are given in Stickel & Kuehr (1993b). 0703+426 : The listed identification and magnitude refers to the radio component A of Kapahi (1981). 0703+468 : The identification and optical magnitude were taken from Stanghellini et al. (1993) 0707+476 : The identification and magnitude have been taken from Meisenheimer & Roeser (1983). The redshift was derived from a spectrum taken by one of us (H.K.) with the Steward Observatory 90" telescope. 0707+689 : The optical spectrum and redshift are given in Stickel & Kuehr (1993b). The redshift has also been measured by Xu et al. (1993). 0710+439 : The identification and magnitude were taken from Stanghellini et al. (1993) The redshift is listed in Pearson & Readhead (1988). 0723+679 : The overall radio spectral index is alpha = -0.52 (Kuehr et al. 1981a), steeper than the two-point spectral index between 11 and 6 cm of alpha_{11-6} = -0.30; this source should therefore be classified as a steep spectrum source. 0727+409 : The redshift is derived from a spectrum taken with the Mount Palomar 5m telescope (Kuehr et al. 1993). 0733+597 : The redshift is derived from a spectrum taken by one of us (H.K.) with the Steward Observatory 90" telescope. 0749+540 : The classification as a BL Lac object and the featureless optical spectrum are given in Stickel & Kuehr (1993b). 0805+410 : The redshift has been taken from Xu et al. (1993). 0806+426 : The identification, magnitude, and redshift were taken from Strom et al. (1990). 0814+425 : The uncertain redshift is due to Wills & Wills (1976). However, the observations of Dunlop et al. (1989) and Stickel et al. (1993b) showed only a featureless spectrum. 0816+526 : The redshift has been taken from Owen et al. (1988). 0859+681 : The redshift was derived from a spectrum taken by one of us (H.K.) with the Steward Observatory 90" telescope. 0913+391 : The uncertain, single emission line redshift of Allington-Smith et al. (1988) is confirmed by a spectrum taken by one of us (H.K.) with the Steward Observatory 90" telescope, which showed the C IV 1549 and C III] 1909 emission lines. 0917+624 : The optical spectrum and the redshift are given in Stickel & Kuehr (1993b). The redshift previously listed by Quirrenbach et al. (1989) and Qian et al. (1991) was derived from a spectrum taken with the Mount Palomar 5m telescope (Kuehr et al. 1993). 0929+533 : The redshift was derived from spectra taken by one of us (H.K.) with the Steward Observatory 90" telescope and the Multiple Mirror Telescope. 0945+664 : The identification and magnitude have been taken from Bolton & Ekers (1966). 1014+392 : The identification and optical magnitude have been taken from Riley (1975). This radio source lies in the direction of the cluster Abell 963, but the redshift of the optical counterpart has not been directly measured. The redshift given in Burbidge & Crowne (1979) refers to the central cluster galaxy. 1017+487 : The optical and radio data have been taken from van Breugel & J"agers (1982). 1020+400 : The redshift has been taken from Xu et al. (1993). 1030+611 : The redshift is derived from a single broad emission line identified with Mg II 2798, which was detected in a spectrum taken by one of us (H.K.) with the Multiple Mirror Telescope. 1031+567 : The identification and magnitude have been taken from Stanghellini et al. (1993). The redshift is listed in Dunlop et al. (1989). 1128+385 : The redshift has been taken from by Xu et al. (1993). 1144+402 : The redshift is based on C IV 1549, C III] 1909 and Mg II 2798 emission lines detected in a spectrum taken by one of us (H.K.) with the Multiple Mirror Telescope. The redshift has also been measured by Xu et al. (1993). There is a rather poor agreement between these redshift measurements and the value given by Vigotti et al. (1990). 1144+542 : The redshift has been taken from Xu et al. (1993). 1152+551 : The listed identification and magnitude refer to component B of Kapahi (1981). The optical spectrum and redshift are given in Stickel & Kuehr (1993a). 1203+645 : An incorrect redshift is listed by Herbig & Readhead (1992). 1216+487 : The optical spectrum and redshift is given in Stickel & Kuehr (1993c). 1225+368 : The redshift, taken from Herbig & Readhead (1992), has also been measured by Xu et al. (1993). 1242+410 : The redshift has been taken from Xu et al. (1993). 1244+492 : The optical spectrum and redshift is given in Stickel & Kuehr (1993c), which confirms the uncertain redshift listed by Walsh et al. (1979). 1325+437 : The redshift was derived from a spectrum taken by one of us (H.K.) with the Steward Observatory 90" telescope. 1333+459 : The redshift has also been listed by Xu et al. (1993). 1333+589 : The classification as an optical blank field is due to Kuehr (1977a). 1335+552 : The redshift was derived from a spectrum taken by one of us (H.K.) with the Steward Observatory 90" telescope. 1342+662 : The redshift has also been measured from a spectrum taken by one of us (H.K.) with the Steward Observatory 90" telescope. 1342+663 : The redshift has also been listed by Xu et al. (1993). 1347+539 : The redshift has also been derived from spectra taken by one of us (H.K.) with the Multiple Mirror Telescope and the Steward Observatory 90" telescope. The redshift has also been measured by Xu et al. (1993). 1413+349 : The classification as an optical blank field is due to Peacock et al. (1981), Meisenheimer & Roeser (1983) and Stanghellini et al. (1993). 1418+546 : The optical spectrum and redshift are given in Stickel et al. (1993b). 1441+522 : The identification, optical magnitude and redshift have been taken from Spinrad et al. (1985). The catalogues of Hewitt & Burbidge (1987) and Veron-Cetty & Veron (1991) list a nearby QSO. 1452+502 : The revised classification as a QSO, its magnitude and redshift are given in Stickel & Kuehr (1993a). Since the radio spectral index had not been measured in the original S4 catalogue (Paper I), its value has been derived from the radio fluxes listed in Kuehr et al. (1979). 1504+377 : The revised classification as a galaxy as well as the redshift is given in Stickel & Kuehr (1993c). 1547+507 : The identification and optical magnitude have been taken from Kuehr (1977a). The redshift was derived from a spectrum taken by one of us (H.K.) with the Multiple Mirror Telescope. 1636+473 : The identification and optical magnitude have been taken from Porcas et al. (1980). 1726+455 : The redshift was derived from a spectrum taken by one of us (H.K.) with the Steward Observatory 90" telescope. 1738+476 : Observations described in Stickel & Kuehr (1993b) have resolved the previous contradictory classifications of the optical counterpart. The featureless optical spectrum reported therein is in contrast to the to the spectral features observed by Xu et al. (1993), who suggested a redshift of z = 0.316. 1745+624 : The identification, magnitude, and redshift as well as more detailed discussion of this very high redshift radio selected quasar is given in Becker et al. (1992), Stickel & Kuehr (1993a) and Stickel (1993). 1819+396 : A redshift estimate based on the optical magnitude is listed by Spencer et al. (1989) and Herbig & Readhead (1992), but has not been included in the catalogue. 1833+653 : The optical spectrum and redshift are given in Stickel & Kuehr (1993a). 1843+356 : The uncertain identification as a galaxy and optical magnitude have been taken from Stanghellini et al. (1993). The catalogue of Veron-Cetty & Veron (1991) lists a nearby QSO, which is not associated with the S4 radio source. 1843+400 : The identification and optical magnitude have been taken from Kuehr (1977a). 1849+670 : The optical spectrum and redshift are given in Stickel & Kuehr (1993a). 1850+402 : Since the radio spectral index had not been measured in the original S4 catalogue (Paper I), its value has been derived from the radio fluxes listed in Kuehr et al. (1979). 1851+488 : The identification and optical magnitude have been taken from Kuehr (1977a). 1926+611 : The featureless optical spectrum described in Stickel & Kuehr (1993a,c) has been confirmed by Xu et al. (1993). Since the radio spectral index had not been measured in the original S4 catalogue (Paper I), its value has been derived from the radio fluxes listed in Kuehr et al. (1979). 1943+546 : The magnitude, optical spectrum, and redshift are given in Stickel & Kuehr (1993a). 2015+657 : The identification and magnitude have been taken from O'Dea et al. (1991). The optical spectrum and redshift are given in Stickel & Kuehr (1993b). 2207+374 : The redshift has been taken from Xu et al. (1993). 2218+395 : The optical spectrum and redshift are given in Stickel & Kuehr (1993b). 2255+416 : The identification and magnitude were taken from Fugmann & Meisenheimer (1988). The optical spectrum and the redshift is given in Stickel & Kuehr (1993c). The spectral features described therein are in contrast to those listed by Xu et al. (1993), who suggested a redshift of z = 1.724. 2311+469 : The optical spectrum and redshift are given in Stickel & Kuehr (1993b). The redshift has also been measured by Thompson et al. (1992) and Xu et al. (1993). 2323+435 : The identification and magnitude were taken from Edwards et al. (1975). The optical spectrum and redshift are given in Stickel et al. (1993a). Although the two-point radio spectral index between 11 and 6 cm is alpha_{11-6} = -0.47, the overall radio spectrum ist steeper (Kuehr et al. 1981a) and the radio morphology is heavily resolved (Ulvestad et al., 1981). Therefore, this source should be classified as a steep spectrum radio source. 2324+405 : The identification and magnitude were taken from Cohen et al. (1977). The optical spectrum and redshift are given in Stickel & Kuehr (1993b). Although the two-point radio spectral index between 11 and 6 cm is alpha_{11-6} = -0.48, the overall radio spectrum ist steeper (Kuehr et al. 1981a) and this source should therefore be classified as a steep spectrum radio source. 2356+385 : The optical spectrum and redshift is given in Stickel & Kuehr (1993c). The uncertain redshift suggested by Wills et al. (1992) is incorrect. 2356+436 : The uncertain identification and magnitude have been taken from Gunn et al. (1981), while the redshift is listed in McCarthy (1988). 2351+456 : The optical spectrum and redshift are given by Stickel & Kuehr (1993b).