van Nao, Tran. 1983. ?Agroforestry Systems And Some Research Problems?. In Plant Research And Agroforestry: Proceedings Of A Consultative Meeting Held In Nairobi, 8 To 15 April 1981, 71-77. Nairobi, Kenya: International Council for Research in Agroforestry. http://www.worldcat.org/oclc/11698847.