Tyteca, D., M. Ceinos, J.-L. Gathoye, R. Brys, and H. Jacquemyn. β€œOn the Morphological, Biological and Genetic Heterogeneity of the Genus Orchis (Orchidaceae, Orchidinae)”. Phytotaxa, vol. 75, no. 1, Dec. 2012, pp. 19–32, doi:10.11646/phytotaxa.75.1.2.