APA Format
Elwood, J. Mark . (). Causal relationships in medicine : a practical systems for critical appraisal. :
MLA Format
Elwood, J. Mark . Causal relationships in medicine : a practical systems for critical appraisal. : ,
Australian/Harvard Format
Elwood, J. Mark . . Causal relationships in medicine : a practical systems for critical appraisal. , 
Warning: These citations may not always be 100% accurate.