Jakobsen, M A, Hult, A K, Hellberg, Å, Crottet, S L, Sprogøe, U & Olsson, M L 2020, ' A novel ABO allele with a 21-bp duplication identified in two unrelated European individuals with weak A expression ', Transfusion Medicine, vol. 30, no. 6, pp. 508-512 . https://doi.org/10.1111/tme.12730