Evidence-based medicine

General references
Evidence-based medicine Wikipedia
Evidence-based practice Wikipedia
Evidence-based practice centers AHRQ

C. difficile infection
Clostridium Difficile (NEJM 2008)

Hyponatremia causes
Diuretic – http://www.uptodate.com/contents/diuretic-induced-hyponatremia
Hypothyroidism – http://www.uptodate.com/contents/hyponatremia-in-hypothyroidism
SSRI – http://www.slackjournals.com/article.aspx?rid=4981

UTI
National Guideline Clearinghouse