RT Journal Article SR Electronic T1 Closing the therapeutic gap in patients with low vitamin B12 levels JF Clinical Medicine JO Clin Med FD Royal College of Physicians SP 190 OP 190 DO 10.7861/clinmedicine.12-2-190 VO 12 IS 2 A1 Linda JE Walker YR 2012 UL http://www.rcpjournals.org/content/12/2/190.abstract