1. On the existence of positive solutions of semilinear elliptic equations;Lions;SIAM Rev.,1982
2. Nonlinear eigenvalue problems with semipositone structures;Castro;Electron. J. Fiff. Eqns.,2000
3. A. Castro, M. Chhetri, R. Shivaji, Positivity of nonnegative solutions for cooperative semipositone systems, in: Dynamic Systems and Applications, (Atlanta, GA, 1999) Dynamic, Atlanta, GA, 2001, (3) pp 113–119
4. Positive solutions for semipositone systems in the annulus;Hai;Rocky Mountain J. Math,1999
5. An existence result for positive solutions for a class of semilinear elliptic system;Hai;Proc. Roy. Soc. Edinb.,2004