References

• Allen D.A, Ward M.J., Hyland H.R., 1982, MNRAS 199, 969 NASA ADS
• Angel J.R.P., Stockman H.S., 1980, ARA&A 8, 321
• Bailey J., Hough J.H., Axon D.J., 1983, MNRAS 203, 339 NASA ADS
• Biraud F., Véron P., 1968, Nat 219, 254
• Bregman J.N., Glassgold A.E., Huggins P.J., et al., 1990, ApJ 352, 574 NASA ADS
• Brown L.M.J., Robson E.I., Gear W.K., Smith M.G., 1989, ApJ 340, 150 NASA ADS
• Carswell R.F., Strittmatter P.A., Williams S.R., et al., 1974, ApJ 190, L101 NASA ADS
• Catanese M., Akerlof C.W., Williams R.E., et al., 1997, ApJ 480, 562 NASA ADS
• Cruz-Gonzalez I., Huchra J.P., 1984, AJ 89, 441 NASA ADS
• De Diego J.A., Kidger M.R., Gonzales-Perez J.N., Lehto H.J., 1997, A&A 318, 331 NASA ADS
• DuPuy D., Schmitt J., McClure R., van den Bergh S., Racine R., 1969, ApJ 156, L135 NASA ADS
• Epstein E.E., Fogarty W.G., Hachney K.R., et al., 1972, ApJ 178, L51
• Fan J.H., Feng X.C., 1998, Publ. of Yunnan Observatory (in press)
• Fan J.H., Xie G.Z., Pecontal E., et al., 1998, ApJ (accepted)
• Fan J.H., Cheng K.S., Zhang L., Liu C.H., 1997, A&A 327, 947 NASA ADS
• Fan J.H., Xie G.Z., Wen S.L., 1996, A&AS 116, 409 NASA ADS
• Fan J.H., 1993, Ph.D. Thesis, Yunnan Astronomic Observatory, Chinese Academy of Sciences
• Gabuzda D.C., 1989, ApJ 347, 701 NASA ADS
• Gear W.K., 1993, MNRAS 264, 919 NASA ADS
• Gear W.K., Robson E.I., Ade P.A.R., et al., 1985, ApJ 291, 511 NASA ADS
• George I.M., Warwick R.S., Bromage G.E., 1988, MNRAS 232, 793 NASA ADS
• Gower J.F.R., 1969, Nat 224, 569
• Heidt J., Wagner S.J., 1995, A&A 305, 42 NASA ADS
• Holmes P.A., Brand P.W.J.L., Wolstencroft R.D., Williams, P.M., 1984, MNRAS 210, 961 NASA ADS
• Impey C.D., Brand P.W.J.L., Wolstencroft R.D., Williams P.M., 1982, MNRAS 200, 19 NASA ADS
• Impey C.D., 1983, MNRAS 202, 397 NASA ADS
• Impey C.D., Brand P.W.J.L., Wolstencroft R.D., Williams P.M., 1984, MNRAS 209, 245 NASA ADS
• Kawai N., Matsuoka M., Bregman J.N., et al., 1991, ApJ 382, 508 NASA ADS
• Kerrick A.D., Akerlof C.W., Biller S., et al., 1995, ApJ 452, 588 NASA ADS
• Knacke R.F., Capps R.W., Johns M., 1976, ApJ 210, L69 NASA ADS
• Litchfield S.L., Robson E.I., Stevens J.A., 1994, MNRAS 270, 341 NASA ADS
• MacLeod J.M., Andrew B.H., 1968, ApL 1, 243
• Massaro E., Nesci R., Perda G.C., et al., 1995, A&A 299, 339 NASA ADS
• Mead A.R.G., Ballard K.R., Brand P.W.J.L., et al., 1990, A&AS 83, 183 NASA ADS
• Miller J.S., 1978, Comm. Astrophys. 7, 175 NASA ADS
• Moore R.L., McGraw J.T., Angel J.R.P., et al., 1982, ApJ 260, 415 NASA ADS
• Morini M., Chiappetti L., Maccagni D., et al., 1986, ApJ 306, L71 NASA ADS
• O'Dell S.L., Pushell J.J., Stein W.A., 1977, ApJ 213, 351 NASA ADS
• O'Dell S.L., Pushell J.J., Stein W.A., Warner J.W., 1978a, ApJS 38, 267 NASA ADS
• Oke J.B., Gunn J.E., 1974, ApJ 189, L5 NASA ADS
• Oke J.B., Neugebauer G., Becklin, 1969, ApJ 156, L41 NASA ADS
• Pica A.J., Pollock J., Smith A.G., et al., 1980, AJ 85, 1442 NASA ADS
• Puschell J.J., Jones T.W., Pillips A., et al., 1983, ApJ 265, 625 NASA ADS
• Quinn J., et al., 1995, in Prof. 24th Int. Cosmic Ray Conf. (Rome) 2, 369
• Sandage A., 1972, ApJ 178, 1 NASA ADS
• Schramm K.J., Borgeest U., Kuhl D., et al., 1994, A&AS 106, 349 NASA ADS
• Sillanpaa A., Mikkola S., Valtaoja L., 1991, A&AS 88, 225 NASA ADS
• Sitko M.L., Sitko A.K., 1991, PASP 103, 160 NASA ADS
• Sitko M.L., Schmidt G.D., Stein W.A., 1985, ApJS 59, 323 NASA ADS
• Sitko M.L., Stein W.A., Zhang Y.X., Wisniewski W.Z., 1983, PASP 95, 724 NASA ADS
• Smith P.S., Balonek T., Elston R., Heckert P.A., 1987, ApJS 64, 459 NASA ADS
• Soifer B.T., Neugebauer G., 1980, IAU Symps. 90, 329
• Stein W.A., O'Dell S.L., Strittmatter P.A., 1976, ARA&A 14, 173 NASA ADS
• Strittmatter P.A., Carswell R.F., Stein W.A., et al., 1972, ApJ 175, L7 NASA ADS
• Takalo L.O., Sillanpaa A., Nilsson K., et al., 1992, A&AS 94, 37 NASA ADS
• Takalo L.O., Sillanpaa A., Pursimo T., et al., 1996, A&AS 120, 313 NASA ADS
• Thompson D.J., Bertsch D.L., Dingus B.L., et al., 1995, ApJS 101, 259 NASA ADS
• Thompson D.J., Bertsch D.L., Dingus B.L., et al., 1996, ApJS 107, 227 NASA ADS
• Thuan T.X., Oke J.B., Gunn J.E., 1975, ApJ 201, 45 NASA ADS
• Tornikoski M., Valtaoja E., Terasranta H., et al., 1994, A&A 289, 673 NASA ADS
• Vermeulen R.C., Cohen M.H., 1994, ApJ 430, 467 NASA ADS
• Urry C.M., 1984, Ph.D. Thesis, the Univ. of Hopkins
• Véron-Cetty M.P., Véron P., 1996, ESO Sci. Report, No. 17
• Véron P., 1978, in Pittb. Conf. on BL Lac Objects, Wolf A. (ed.), p. 20
• Webb J.R., Smith A.G., Leacock R.J., et al., 1988, AJ 95, 374 NASA ADS
• Weistrop D., 1973, Nat 241, 157
• Weistrop D., Goldsmith S., 1973, ApL 14, 225 NASA ADS
• Whitford A.E., 1958, ApJ 107, 102
• Wills B.J., Wills D., Breger M., et al., 1992, ApJ 398, 454 NASA ADS
• Xie G.Z., Lu R.W., Zhou Y., et al., 1988, A&AS 72, 163 NASA ADS
• Xie G.Z., Li K.H., Zhang Y.H., et al., 1994, A&AS 106, 361 NASA ADS