Schelhaas, M., Glomsda, S., Hansler, M., Jakubke, H., & Waldmann, H. (1996). Enzymatic synthesis of peptides and Ras lipopeptides employing choline ester as a solubilizing, protecting, and activating group. ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 35(1), 106-109. doi:10.1002/anie.199601061.