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N. K. B.  Robson, ?A new species of Hypericum from Angola.?, Bol. Soc. Brot., ser. 2, vol. 53, pp. 113 - 121 (1979 - 80 publ. 1980) - illus., map, key., 1980.

N. K. B.  Robson, ?Hypericum olympicum: wild and cultivated.?, Plantsman, vol. 1, pp. 193 - 200 (1980) - col. illus., map, chrom. no., key., 1980.