1. University of California Ext.San DiegoCA92123
2. Dep. of Agronomy and Range ScienceUniv. of CaliforniaDavisCA95616
3. Dep. of Plant and Soil ScienceCalifornia Polytechnic Inst.PomonaCA
4. School of Agric. ScienceIndependent Univ. of Baja CaliforniaMexico