The 1991 World Book Year Book. Chicago etc.: World Book, 1991 576 p. : ill. 0-7166-0491-4.
The 1991 World Book Year Book. Chicago etc.: World Book, 1991 576 p. : ill. 0-7166-0491-4.
(1991) The 1991 World Book Year Book, Chicago etc.: World Book 576 p. : ill. 0-7166-0491-4.
(1991). The 1991 World Book Year Book. The Annual Supplement to The World Book Encyclopedia : A Review of the Events of 1990. Chicago etc.: World Book, 576 p. : ill.
The 1991 World Book Year Book: The Annual Supplement to The World Book Encyclopedia : A Review of the Events of 1990. Chicago etc.: World Book; 1991. p. 576 p. : ill. ISBN: 0-7166-0491-4.