APA
WHO, . (2001). International travel and health: vaccination requirements and health advice situation as on 1 jan- 2001. Geneva: WHO Regional Publications.
Chicago
WHO, . 2001. International travel and health: vaccination requirements and health advice situation as on 1 jan- 2001. Geneva: WHO Regional Publications.
Harvard
WHO, . (2001). International travel and health: vaccination requirements and health advice situation as on 1 jan- 2001. Geneva: WHO Regional Publications.
MLA
WHO, . International travel and health: vaccination requirements and health advice situation as on 1 jan- 2001. Geneva: WHO Regional Publications. 2001.