N. K. B.  Robson, ?Studies in the genus Hypericum L. (Guttiferae): 7. Section 29. Brathys (part 1).?, Bull. Brit. Mus. (Nat. Hist.) Bot., vol. 16, p. 106p. (1987) - illus., maps., 1987.

N. K. B.  Robson, ?Studies in the genus Hypericum L. (Guttiferae): 8. Sections 29. Brathys (part 2) and 30. Trigynobrathys.?, Bull. Brit. Mus. (Nat. Hist.) Bot., vol. 20, pp. 1-151 (1990) - illus., maps., 1990.

N. K. B.  Robson, ?Studies in the genus Hypericum L. (Guttiferae): 2. Characters of the genus.?, Bull. Brit. Mus. (Nat. Hist.) Bot., vol. 8, pp. 55 - 226 (1981) - illus., chrom. nos., maps., 1981.