title: Paying for bmj.com: is this measure scientific literature's half open sesame?
authors.forename: Clarence C
authors.initials: CC
authors.lastname: Tam
authors.forename: Ben A
authors.initials: BA
authors.lastname: Lopman
authors.forename: Dina
authors.initials: D
authors.lastname: Handan
mesh_terms: D005249:Fees and Charges; D033181:Information Dissemination; D020407:Internet / Q000600:supply & distribution; D010506:Periodicals as Topic / Q000191:economics / Q000600:supply & distribution*; D006113:United Kingdom