Will, Colin. 2010. “The European Garden Flora; a Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and under Glass. Volume III, Dicotyledones (Part I), Edited by S.M. Walters and Others”. Edinburgh Journal of Botany 48 (1): 131-32. https://doi.org/10.1017/S0960428600003711.