Liên kết ngoài 
 Lecture notes on angiosperms from University of Maryland 
 Article on the Korean bellflower
 Article on Abeliophyllum distichum by Yong Shik Kim and Mike Maunder from CURTIS'S Botanical Magazine, Royal Botanic Gardens, Kew, UK. Vol. 15(2): 141-146, 1998.
 Takenoshin Nakai 1882-1952 by Hiroshi Hara