Pearl, Irwin A.; Darling, Stephen F.; Justman, Oliver (1962). "Studies on the Leaves of the Family Salicaceae. I. Populin from the Leaves of Populus grandidentata and Populus tremuloides". The Journal of Organic Chemistry. 27 (7): 2685–2687. doi:10.1021/jo01054a538. ISSN0022-3263.
Pearl, Irwin A.; Darling, Stephen F.; Justman, Oliver (1962). "Studies on the Leaves of the Family Salicaceae. I. Populin from the Leaves of Populus grandidentata and Populus tremuloides". The Journal of Organic Chemistry. 27 (7): 2685–2687. doi:10.1021/jo01054a538. ISSN0022-3263.