Robson, NORMAN K. B. (2013-05-14). "Studies in the genus Hypericum L. (Hypericaceae) 5(1). Sections 10. Olympia to 15/16. Crossophyllum". Phytotaxa. 4 (1): 5. doi:10.11646/phytotaxa.4.1.2. ISSN1179-3163.
Robson, NORMAN K. B. (2013-05-14). "Studies in the genus Hypericum L. (Hypericaceae) 5(1). Sections 10. Olympia to 15/16. Crossophyllum". Phytotaxa. 4 (1): 5. doi:10.11646/phytotaxa.4.1.2. ISSN1179-3163.