Reference

Mary Gibby, C.-J. Widén, Hely Katriina Widén (1978): Cytogenetic and Phytochemical Investigations in Hybrids of Macaronesian Dryopteris (Pteridophyta: Aspidiaceae) – Österreichische Botanische Zeitschrift = Plant Systematics and Evolution – 130: 235 - 252.