Umponstira, Chanin, 		Kawayaskul, Srisuda, 		Chuchaung, Sasinapa, AND 		Homhaul, Wipa.
" Effect of Ozone on Nitrogen Fixation, Nitrogenase Activity and Rhizobium of Cowpea (Vigna unguiculata (L.) Walp)" <em>Naresuan University Journal: Science and Technology (NUJST)</em> [Online], Volume 17 Number 3 (29 July 2013)