Dariana 2010. Keanekaragaman Nepenthes dan pohon inang di Taman Wisata Alam Sicikeh-Cikeh Kabupaten Dairi Sumatera Utara. M.Sc. thesis, University of North Sumatra, Medan. Heng, S.B. 2013. There's big money in pitcher plants. New Straits Times, July 13, 2013. External links Photographs of N. rigidifolia at the Carnivorous Plant Photofinder Carnivorous plants of Asia rigidifolia Endemic flora of Sumatra Plants described in 2004 Species endangered by the pet trade