REFERENCES TO TABLES 2, 3, 4 AND 5 BY REFERENCE NUMBER CODE
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 02   Tananbaum, H., et al. 1979, Ap.J. (Letters), 234, L9.
 03   Zamorani, G., et al. 1981, Ap.J., 245, 357.
 04   Tananbaum, H., et al. 1983, Ap.J., 268, 60.
 05   Elvis, M., and Fabbiano, G. 1984, Ap.J., 280, 91.
 06   Henriksen, M.J., Marshall, F.E., and Mushotzky, R.F. 1984, 
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 07   Elvis, M., Wilkes, B.J., and Tananbaum, H. 1985, Ap.J., 292, 357.
 08   Arnaud, K.A., et al. 1985, M.N.R.A.S., 217, 105.
 09   Turner, M.J.L., et al. 1985, Space Sci. Rev., 40, 623.
 10   Fabbiano, G., et al. 1984, Ap.J., 277, 115.
 11   Worrall, D.M., and Marshall, F.E. 1984, Ap.J., 276, 434.
 12   Petre, R., et al. 1984, Ap.J., 280, 499.
 13   Ulmer, M.P., et al. 1983, Ap.J. (Letters), 270, L1.
 14   Staubert, et al. 1986, Astr. Ap., 162, 16.
 15   Perola, G.C., et al. 1986, Ap.J., 306, 508.
 16   Bregman, J.N., et al. 1985, Ap.J., 291, 505.
 17   Fabbiano, G., Feigelson, E., and Zamorani, G. 1982, Ap.J., 256, 397.
 18   Halpern, J.P., et al. 1986, Ap.J., 302, 711.
 19   Shrader, C.R., Wood, K.S., and Matilsky, T. 1986, Ap.J. Suppl., 61, 353.
 20   Warwick, P., et al. 1986, M.N.R.A.S., 219, 39.
 21   Giommi, P., et al. 1986, Ap.J., 303, 596.
 22   Urry, C.M., Mushotzky, R.F., and Holt, S.S. 1986, Ap.J., 305, 369.
 23   Feigelson, E.D., et al. 1986, Ap.J., 302, 337.
 24   Bradt, H., et al. 1985, Space Sci. Rev., 40, 613.
 25   Stoke, J.T., et al. 1985, Ap.J., 298, 619.
 26   Singh, K.P., and Garmire, G.P. 1985, Ap.J., 297, 199.
 27   Ledden, J.E., and O'Dell, S.L. 1985, Ap.J., 298, 630.
 28   Reichert, G.A., et al. 1985, Ap.J., 296, 69.
 29   Morini, M. et al. 1985, Space Sci. Rev., 40, 601.
 30   Canizares, C.R., and Kruper, J. 1984, Ap.J. (Letters), 278, L99.
 31   Worrall, D.M. et al. 1984, Ap.J., 278, 521.
 32   Maccacaro, T., et al. 1984, Ap.J. (Letters), 284, L23.
 33   Madejsky, G.M., and Schwartz, D.A. 1983, Ap.J., 275, 467.
 34   Maccagni, D., Maccacaro, T., and Tarenghi, M. 1983, Ap.J., 273, 70.
 35   Morini, M., et al. 1986, Ap.J. (Letters), 306, L71.
 36   Barr, P. 1986, M.N.R.A.S., 223, 29P.
 37   Urry, C.M., and Mushotzky, R.F. 1982, Ap.J., 253, 38.
 38   Snyder, W.A., et al. 1982, Ap.J., 259, 38.
 39   Urry, C.M., et al. 1982, Ap.J., 261, 12.
 40   Marshall, N., Warwick, R.S., and Pounds, K.A. 1981, M.N.R.A.S., 194, 987.
 41   Riegler, G.R., Agrawal, P.C., and Mushotzky, R.F. 1979, 
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 42   Worrall, D.M., et al. 1981, Ap.J., 243, 53.
 43   Kondo, Y., et al. 1981, Ap.J., 243, 690.
 44   Maccagni, D., and Tarenghi, M. 1981, Ap.J., 243, 42.
 45   Maccagni, D., and Tarenghi, M., 1981, Space Sci. Rev., 30, 55.
 46   Snyder, W.A., et al. 1980, Ap.J. (Letters), 237, L11.
 47   Schwartz, D.A., et al. 1979, Ap.J. (Letters), 229, L53.
 48   Hearn, D.R., Marshall, F.J., and Jernigan, J.G. 1979, 
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 49   Agrawal, P.C., and Riegler, G.R. 1979, Ap.J. (Letters), 231, L25.
 50   Schwartz, D.A., and Ku, W.H.-M. 1983, Ap.J., 266, 459.
 51   Biermann, P., et al. 1982, Ap.J. (Letters), 252, L1.
 52   Maraschi, L., et al. 1986, Ap.J., 310, 325.
 53   Elvis, M., et al. 1986, Ap.J., 310, 291.
 54   Mushotzky, R.F., et al. 1979, Ap.J. (Letters), 232, L17.
 55   Staubert, R., Brunner, H., and Worrall, D.M. 1986, Ap.J., 310, 694.
 56   Schwartz, D.A., et al. 1978, Ap.J. (Letters), 224, L103.
 57   Mushotzky, R.F., et al. 1978, Ap.J. (Letters), 226, L65.
 58   Brown, L.M.J., et al. 1986, M.N.R.A.S., 219, 671.
 59   Maccacaro, T., Garilli, B., and Mereghetti, S. 1987, A.J., 93, 1484.
 60   Snijders, M.A.J., et al. 1979, M.N.R.A.S., 189, 873.
 61   Griffiths, R.E., et al. 1979, Ap.J., 234, 810.
 62   Elvis, M. 1977, M.N.R.A.S., 177, 7P.
 63   Forman, W., et al. 1978, Ap.J. Suppl., 38, 357.
 64   Ulmer, M.P., et al. 1980, Ap.J., 235, 351.
 65   Margon, B., et al. 1986, P.A.S.P., 98, 1129.
 66   Murray, S.S., and Ulmer, M.P. 1976, Ap.J., 210, 230.
 67   Wall, J.V., et al. 1986, M.N.R.A.S., 219, 23P.
 68   Garilli, B., and Tagliaferri, G., 1986, Ap.J., 301, 703.
 69   Chanan, G.A., et al. 1982, Ap.J. (Letters), 261, L31.
 70   Pounds, K.A., et al. 1986, M.N.R.A.S., 218, 685.
 71   Miyoshy, S., et al. 1986, Ap. and Space Sci., 119, 185.
 72   Matsuoka, M., et al. 1986, P.A.S.J., 38, 285.
 73   Branduardi-Raymont, G., et al. 1985, M.N.R.A.S., 216, 1043.
 74   Bregman, J.N., et al. 1981, Nature, 293, 714.
 75   Lawrence, A., et al. 1985, M.N.R.A.S., 217, 685.
 76   Worrall, D.M., et al. 1984, Ap.J., 284, 512.
 77   Pounds, K.A., et al. 1985, Space Sci. Rev., 40, 585.
 78   Perola, G.C., et al. 1985, Space Sci. Rev., 40, 593.
 79   Singh, K.P., Garmire, G.P., and Nousek, J. 1985, Ap.J., 297, 633.
 80   Baity, W.A., et al. 1984, Ap.J., 279, 555.
 81   Pye, J.P., and McHardy, I.M. 1983, M.N.R.A.S., 205, 875.
 82   Bell Burnell, S.J., and Chiappetti, L. 1984, Astr. Ap. Suppl., 56, 415.
 83   Bregman, J.N., et al. 1984, Ap.J., 276, 454.
 84   Cruz-Gonzales, I., and Huchra, J.P. 1984, A.J., 89, 441.
 85   Ulvestad, J.S., and Wilson, A.S. 1983, A.J., 88, 253.
 86   Elvis, M., Ulrich, G.B., and Henry, J.P. 1983, Ap.J., 268, 105.
 87   Marshall, F.E., et al. 1983, Ap.J. (Letters), 269, L31.
 88   Kriss, G., and Doxsey, R. 1983, P.A.S.P., 95, 133.
 89   Mushotzky, R.F., et al. 1978, in "Pittsburgh Conference on BL Lac 
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 90   Nugent, J.J., et al. 1983, Ap.J. Suppl., 51, 1.
 91   Wood, K.S., et al. 1984, Ap.J. Suppl., 56, 507.
 92   Pounds, K.A. 1985, in "X-Ray Astronomy 1984", eds. R. Giacconi and M. Oda 
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 93   Warwick, R.S., McHardy, I.M., and Pounds, K.A. 1985, in "X-Ray Astronomy 
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 95   Mufson, S.L., et al. 1982, in "Advances in Ultraviolet Astronomy: Four 
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 96   Hutter, D.J., et al. 1982, in "Advances in Ultraviolet Astronomy: Four 
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 97   Elvis, M., and Fabbiano, G. 1982, in "Advances in Ultraviolet Astronomy:
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 98   Dil, S., et al. 1981, Ap.J., 250, 513.
 99   Beall, J.H., et al. 1981, Ap.J., 247, 458.
 100  Hall, R., et al. 1981, Space Sci. Rev., 30, 47.
 101  Branduardi-Raymont, G., et al. 1984, in "X-Ray and UV Emission from 
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 102  Henry, J.P., et al. 1980, Highlights of Astronomy, ed. P.A. Wayman 
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 103  Chubb, T.A. 1978, in "Pittsburgh Conference on BL Lac Objects", ed. A.M. 
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 104  Dower, R.G., et al. 1980, Ap.J., 235, 355.
 105  Hayes, M.J.C., Culhane, J.L., and Bell Burnell, S.J. 1980, 
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 106  Mushotzky, R.F., et al. 1980, Ap.J., 235, 377.
 107  Pounds, K.A. 1985, in "Japan-US Seminar on Galactic and Extragalactic 
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 108  Kriss, G.A., Canizares, C.R. and Ricker, G.R. 1980, Ap.J., 242, 492.
 109  McHardy, I.M., et al. 1981, M.N.R.A.S. 197, 893.
 110  Hayes, M.J.C., et al. 1980, M.N.R.A.S. 193, 15P.
 111  Kriss, G.A., and Canizares, C.R. 1982, Ap.J., 261, 51.
 112  Mufson, S.L., et al. 1984, Ap.J., 285, 571.
 113  Levine, A.M., et al. 1984, Ap.J. Suppl., 54, 581.
 114  Tananbaum, H., et al. 1978, Ap.J., 223, 74.
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 116  Schnopper, H.W., et al. 1978, Ap.J. (Letters), 222, L91.
 117  Cooke, B.A., et al. 1978, M.N.R.A.S., 182, 489.
 118  Elvis, M., et al. 1978, M.N.R.A.S., 183, 129.
 119  Worrall, D.M., et al. 1979, Ap.J., 232, 683.
 120  Mushotzky, R.F., Holt, S.S., and Serlemitsos, P.J. 1978, 
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 121  Bradt, H.V., et al. 1979, Ap.J. (Letters), 230, L5.
 122  Primini, F.A., et al. 1979, Nature, 278, 234.
 123  Hutter, D.J. and Mufson, S.L. 1981, A.J., 86, 1585.
 124  Ulmer, M. 1977, Ap.J. (Letters), 218, L1.
 125  Ives, J.C., Sanford, P.W. and Penston, M.W. 1976, 
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 126  Owen, F., Helfand, D.J., and Spangler, S.R. 1981, 
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 127  Barry, P., et al. 1977, M.N.R.A.S., 181, 43P.
 128  Mufson, S.L., and Hutter, D.J. 1981, Ap.J. (Letters), 248, L61.
 129  Biermann, P., et al. 1981, Ap.J. (Letters), 247, L53.
 130  Worrall, D.M., et al. 1982, Ap.J., 261, 403.
 131  Marshall, F.E., et al. 1979, Ap.J. Suppl., 40, 657.
 132  Gioia, I.M., et al. 1984, Ap.J., 283, 495.
 133  Perola, G.C., et al. 1982, M.N.R.A.S., 200, 293.
 134  Doxsey, R., et al. 1983, Ap.J. (Letters), 264, L43.
 135  Tennant, A.F., and Mushotzky, R.F. 1983, Ap.J., 264, 92.
 136  Stocke, J.I., et al. 1983, Ap.J., 273, 458.
 137  Maccagni, D., et al. 1983, Ap.J., 273, 75.
 138  Bregman, J.N., et al. 1982, Ap.J., 253, 19.
 139  Piccinotti, G., et al. 1982, Ap.J., 253, 485.
 140  Maccacaro, T., et al. 1982, Ap.J. 253, 504.
 141  Wilkes, J.B., and Elvis, M. 1987, Ap.J., 323, 243.
 142  Urry, C.M., et al. 1987, in "Variability of Galactic and Extragalactic 
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