APA aipamena

Không rõ. (1979). Computer and Intractability. NOTNXB.

Chicago Style aipamena

Không rõ. Computer and Intractability. NOTNXB, 1979.

MLA aipamena

Không rõ. Computer and Intractability. NOTNXB, 1979.

Kontuz: berrikusi erreferentzia hauek erabili aurretik.