Sisworo, Elsje L., Haryanto, and Ania Citraresmini. 2013. “USING THE N-15 METHOD TO DETERMINE N-SOIL, N-GREEN MANURE, AND N-UREA AVAILABILITY AFTER SIX SEASONS IN AN ALLEY CROPPING SYSTEM”. Jurnal Ilmiah Aplikasi Isotop Dan Radiasi 2 (2):23-34. https://doi.org/10.17146/jair.2006.2.2.571.