Missing or contradictory answers on questionnaires--a valuable source of information.
Joubert
G
G
van der Ryst
E
E
Steyn
F
F
le Roux
J
J
D005260:Female; D015658:HIV Infections / Q000517:prevention & control*; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D008297:Male; D013019:South Africa; D011795:Surveys and Questionnaires