APA
(1968). Index Medicus. U.S.A: US Department of Health Education and Welfare.
Chicago
1968. Index Medicus. U.S.A: US Department of Health Education and Welfare.
Harvard
(1968). Index Medicus. U.S.A: US Department of Health Education and Welfare.
MLA
Index Medicus. U.S.A: US Department of Health Education and Welfare. 1968.