C. Swaminathan, R . S. Vinaya Rai, K. K. Suresh and K . Sivaganam 1993. IMPROVING SEED GERMINATION OF <em>DERRIS</em> <em>INDICA</em> BY VERTICAL SOWING. Journal of Tropical Forest Science (JTFS) . 6, 2 (Dec. 1993), 152–158.