ABELL, G. O. Realm of The Universe#George O. Abell. Saunders College Publishing.
Lua i Stíl Chicago (17ú heag.)ABELL, George O. Realm of The Universe#George O. Abell. Saunders College Publishing.
Lua MLA (8ú heag.)ABELL, George O. Realm of The Universe#George O. Abell. Saunders College Publishing.
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