Zeros for the Gradients of Very Weak Solutions of a Class of Elliptic Equation of Divergence Type
GAO Hong-ya,ZHANG Hua,TONG Yu-xia
Journal of Hebei University (Natural Science Edition) . 2005, (1): 9 -12 .  DOI: 10.3969/j.issn.1000-1565.2005.01.003