81. * Spectral activity of the Seyfert galaxy Markarian 6 in 1970-1991 / V. T. Doroshenko, S. G. Sergeev // Astron. and Astrophys.- 2003.- Vol. 405, No. 3.- P. 909 - 915.

82. * Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. XVI. A 13 year study of spectral variability in NGC 5548 / B. M. Peterson, P. Berling, R. Bertram,.. V. T. Doroshenko,.. Yu. F. Mal’kov,.. N. I. Merkulova,.. V. I. Pronik, S. G. Sergeev, E. A. Sergeeva et al. // The Astrophys. Journ.- 2002.- Vol. 581, No. 1, pt. 1.- P. 197 - 204.

83. * Variability of the broad Balmer emission lines in 3C 390.3 from 1992 to 2000 / S. G. Sergeev, V. I. Pronik, B. M. Peterson, E. A. Sergeeva et al. // The Astrophys. Journ.- 2002.- Vol. 576, No. 2, pt. 1.- P. 660 - 672.

84. * Complex variability pattern in NGC 4151. Variability of the broad emission-line profiles over 11 years / S. G.Sergeev, V. I. Pronik, E. A. Sergeeva // The Astrophys. Journ.- 2001.- Vol. 554, No. 1, pt. 1.- P. 245 – 260.

85. * Monitoring of the optical and 2.5-11.7 mm spectrum and mid-IR imaging of the Seyfert 1 galaxy Mrk 279 with ISO / M. Santos- Lleo, J. Clavel, B. Schulz,.. Yu. F. Malkov,.. V. I. Pronik,.. S. G. Sergeev et al. // Astron. and Astrophys. - 2001. - Vol. 269, No. 1. - P. 57 - 64.

86. * Multiwavelength monitoring of the narrow-line Seyfert 1 galaxy Arakelian 564. III. Optical observations and the Optical-UV- X-ray connection / O. Seminer, P. Romano, R. Bertram,.. V. I. Pronik,.. S. G. Sergeev, E. A. Sergeeva et al. // The Astrophys. Journ. - 2001. - Vol. 561, No. 1, pt. 1. – P. 162 - 170.

87. * Nuclear Activity of NGC 4151 as Inferred from UBVRI Observations in 1989 - 2000 / V. T. Doroshenko, V. M. Luyty, N. G. Bochkarev,.. N. I. Merkulova, S. G. Sergeev,.. K. N. Grankin et al. // Astronomy Letters.- 2001.- Vol. 27.- P. 65 – 73 = Активность ядра NGC 4151 по UBVRI- наблюдениям 1989 – 2000 гг. / В. Т. Дорошенко, В. М. Лютый, Н. Г. Бочкарев,.. Н. И. Меркулова, С. Г. Сергеев,.. К. Н. Гранкин и др. // Письма в Астрон. журн.- 2001.- Т. 27, № 2.- С. 83 – 93.

88. * A spectroscopic and photometric study of short-timescale variability in NGC 55487 / M. Dietrich, C. F. Bender, D. J. Bergmann,.. V. I. Pronik, S. G. Sergeev, E. A. Sergeeva et al. // Astron. and Astrophys. - 2001. - Vol. 371, No. 1. - P. 79 - 92.

89. * Arp 102B: variability patterns of the H-alpha line profile as evidence for gas rotation in the broad-line region / S. G. Sergeev , V. I. Pronik , E. A. Sergeeva // Astron. and Astrophys.- 2000.- Vol. 356, No.1.- P. 41 - 49.

90. * Complex variability pattern in NGC 4151. II. Variable absorption features / S. G. Sergeev, V. I. Pronik, E. A. Sergeeva, Yu. F. Mal'kov // Astron. and Astrophys.- 1999.- Vol. 341, No. 3.- P. 740 - 750.

91. * Hβ and continuum variability in the Seyfert galaxy Akn 120 from Crimean observations during 1974-1990 / V. T. Doroshenko, S. G. Sergeev, V. I. Pronik, K. K. Chuvaev // Astronomy Letters.- 1999.- Vol. 25, No. 9.- P. 569 – 581 = Переменность линии Нβ и континуума сейфертовской галактики AKN 120 по наблюдениям в Крыму в 1974 - 1990 гг. / В. Т. Дорошенко, С. Г. Сергеев, В. И. Проник, К. К. Чуваев // Письма в Астрон. журн.- 1999.- Т. 25, № 9.- С. 658 – 672.

92. * A link between the Hв equivalent width, profile width, BLR size, and optical luminosity from a small sample of well-studied active galactic nuclei / S. G. Sergeev, V. I. Pronik, E. A. Sergeeva, Yu. F. Malkov // The Astron. Journ.- 1999.- Vol. 118, No. 6.- P. 2658 – 2667.

93. * Markarian 6 nucleus since 1992 / S. G. Sergeev, V. I. Pronik, E. A. Sergeeva, Yu. F. Mal’kov // The Astrophys. Journ. Suppl. Ser.- 1999.- Vol. 121, No. 1.- P. 159 – 169.

94. * Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. XV. Long-term optical monitoring of NGC 5548 / B. M. Peterson, A. J. Barth, P. Berlin,.. Yu. F. Malkov,.. V. I. Pronik, S. G. Sergeev, E. A. Sergeeva et al. // The Astrophys. Journ.- 1999.- Vol. 510, No. 2, pt. 1.- P. 659 – 668.

95. * Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. XII. Ground-based monitoring of 3C 390.3 / M. Dietrich, B. M. Peterson, P. Albrecht,.. Yu. F. Malkov,.. V. I. Pronik, S. G. Sergeev, E. A. Sergeeva et al. // The Astrophys. Journ. Suppl. Ser. – 1998. – Vol. 115, No. 2. – P. 185 – 202.

96. * Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. XIV. Intensive optical spectrophotometric observations of NGC 7469 / S. J. Collier, K. Norne, S. Kaspi,.. Yu. F. Malkov,.. V. I. Pronik, S. G. Sergeev et al. // The Astrophys. Journ. – 1998. – Vol. 500, No. 1, pt. 1. – P. 162 – 172.

97. * Complex variability pattern in NGC 4151. I. Sequences on the line-continuum diagram / Yu. F. Malkov, V. I. Pronik, S. G. Sergeev // Astron. and Astrophys.- 1997.- Vol. 324.- P. 904 – 914.

98. * Photometry and spectrophotometry of the seyfert galaxy MRK 509 over 23 years Photometry and Spectrophotometry of The Seyfert Galaxy MRK 509/ V. T. Doroshenko, K. K. Chuvaev, S. G. Sergeev, V. I. Pronik, Yu. F. Malkov // Astrophys. and Space Sci.- 1997.- Vol. 252, No. 1 - 2.- P. 85 - 94.

99. * [0 III] л 5007 wing variation and changes of Fe II optical multimplets in NGC 5548 / S. G. Sergeev, V. I. Pronik, Yu. F. Malkov, K. K. Chuvaev // Astron. and Astrophys.- 1997.- Vol. 320, No. 2.- P. 405 – 414.

100. * Spectrophotometry of the Seyfert 1 galaxy Mrk 509 from 1972-1993 near H beta / K. K. Chuvaev, V. T. Doroshenko, S. G. Sergeev, V. I. Pronik, Yu. F. Mal’kov // Astronomy Letters.- 1997.- Vol. 23, No. 3.- P. 355 – 369 = Спектрофотометрия сейфертовской галактики I типа Маркарян 509 в 1972-1993 гг. область Нβ / К. К. Чуваев, В. Т. Дорошенко, С. Г. Сергеев, В. И. Проник, Ю. Ф. Мальков // Письма в Астрон. журн.- 1997.- Т. 23, № 6.- С. 409 – 425.