http://www.aafp.org/afp/2011/0615/p1425.html http://www.aafp.org/afp/2011/0615/p1425.html http://www.aafp.org/afp/2011/0615/p1425.html http://www.aafp.org/afp/2011/0615/p1425.html American Family Physician: Update on Vitamin B12 Deficiency http://www.aafp.org/afp/2011/0615/p1425.html http://www.aafp.org/afp/2011/0615/p1425.html