Bernard Verdcourt 
Flora of Tropical East Africa – Polypodiaceae (2001) [PDF ebook] 

Part of a series on the flora of tropical East Africa, this work considers Polypodiaceae. The flora is prepared at Royal Botanic Gardens, Kew in close collaboration with East African Herbarium and in liaison with the University of Dar es Salaam, the University of Nairobi and the Makerere University. Significant contributions are also made by specialists from elsewhere. The flora should be a useful reference for anyone concerned with the identification and utilization of plants in eastern Africa. Each family is published as a separate part. New parts are published annually.