Tier 4 — Primary research

1 source. Lower tiers are used only where higher tiers are silent, and the reason is recorded on the source.

Elective Liver Transplant List Mortality: Development of a United Kingdom End-Stage Liver Disease Score Barber K, Madden S, Allen J, et al. · 2011-08-27 · Tier 4
Current — checked with the publisher on 2026-09-01 · unread