C. R. Lynds, Astrophys. J.,147, 396 (1967).
J. D. Scargle, L. J. Caroff, and P. D. Noerdlinger, Astrophys. J.,161, L115 (1970).
L. B. Lucy, Astrophys. J.,163, 95 (1971).
D. van Blerkom, in: Wolf-Rayet and High-Temperature Stars, IAU Sympos. No. 49, Buenos Aires, Aug. 1971, Reidel (1973), p. 165.
L. J. Caroff, P. D. Noerdlinger, and J. D. Scargle, Astrophys. J.,176, 439 (1972).
V. V. Sobolev, Moving Envelopes of Stars [English translation], Harvard Univ. Press (1960).
V. V. Sobolev, Astron. Zh.,34, 694 (1957).
C. W. Allen, Astrophysical Quantities, Ist ed., London Univ. Press (1955).
R. F. Mushotzky, P. M. Solomon, and P. A. Strittmatter, Astrophys. J.,174, 7 (1972).
C. B. Tarter and C. F. McKee, Astrophys. J.,186, L63 (1973).
É. A. Dibai and V. I. Pronik, Astron. Zh.,44, 952 (1967).
G. A. Shields, J. B. Oke, and W. L. W. Sargent, Astrophys. J.,176, 75 (1972).
E. M. Burbidge, Astrophys. J.,152, L111 (1968).
E. M. Burbidge, Astrophys. J.,155, L43 (1969).
