©2013 National Research Council of Thailand
Harper และผู้แต่งคนอื่นๆ. 1986. Sustainable agriculture on slopes : the effectiveness of international development projects in fostering soil conservation in North Thailand. Hawaii:University of Hawaii;
Harper และผู้แต่งคนอื่นๆ. (1986) Sustainable agriculture on slopes : the effectiveness of international development projects in fostering soil conservation in North Thailand (รายงานผลงานวิจัย). University of Hawaii:Hawaii.
Harper และผู้แต่งคนอื่นๆ. Sustainable agriculture on slopes : the effectiveness of international development projects in fostering soil conservation in North Thailand. Hawaii:University of Hawaii, 1986.
Harper และผู้แต่งคนอื่นๆ. (1986) Sustainable agriculture on slopes : the effectiveness of international development projects in fostering soil conservation in North Thailand (รายงานผลงานวิจัย). University of Hawaii:Hawaii.