(1978). Facts in focus. Penguin.
Chicago Style (17th ed.) CitationFacts in Focus. Harmondsworth: Penguin, 1978.
MLA (9th ed.) CitationFacts in Focus. Penguin, 1978.
Advarsel: Disse citationer er muligvist ikke 100% nøjagtige.
(1978). Facts in focus. Penguin.
Chicago Style (17th ed.) CitationFacts in Focus. Harmondsworth: Penguin, 1978.
MLA (9th ed.) CitationFacts in Focus. Penguin, 1978.