APA-referens (7:e uppl.)

ABELL, G. O. (1980). Realm of the universe.-- Ed.2. Saunders College.

Chicago-referens (17:e uppl.)

ABELL, George O. Realm of the Universe.-- Ed.2. Philadelphia: Saunders College, 1980.

MLA-referens (9:e uppl.)

ABELL, George O. Realm of the Universe.-- Ed.2. Saunders College, 1980.