APA

Sharma O. P., . (1978). Textbook of gymnosperms. : Pragati Prakashan, Agra.

Chicago

Sharma O P, . 1978. Textbook of gymnosperms. : Pragati Prakashan, Agra.

Harvard

Sharma O. P., . (1978). Textbook of gymnosperms. : Pragati Prakashan, Agra.

MLA

Sharma O P, . Textbook of gymnosperms. : Pragati Prakashan, Agra. 1978.