I.  Hagemann, ?On subspecific taxa of Hypericum empatrifolium (Hypericaceae) from Crete.?, Pl. Syst. Evol., vol. 155, pp. 165-187 (1987) - illus., map., 1987.

T.  Kato, ?Taxonomical studies on the Hypericum pseudopetiolatum complex: 3. Taxonomy.?, Bull. Nation. Sci. Mus., B (Tokyo), vol. 13, pp. 69-80 (1987) - illus., 1987.

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, ?An Iranian floristic link with Socotra in Hypericum (Hypericaceae).?, Pl. Syst. Evol., vol. 155, pp. 89-92 (1987) -, 1987.