Զեկուցիր օբյեկտի հետ կապված խնդիրը: The MK-process and stellar classification. Proceedings of the Workshop in honour of W. W. Morgan and Ph. C. Keenan held at the University of Toronto, Canada June 1983. Ed. R. F. Garrison. David Dunlap Observatory, University of Toronto, Canada, 1984, 423 p