References
- Guo , Dajun and Lakshmikantham , V. 1987 . Coupled fixed points of nonlinear operators with applications . Nonlinear Anal. TMA , 11 : 623 – 632 .
- Guo , Dajun . 1988 . Fixed points of mixed monotone operators with applications . Appl. Anal. , 31 : 215 – 224 .
- Guo , Dajun and Lakshmikantham , V. 1988 . Nonlinear problems in abstract cones , Boston & New york : Academic Press,Inc .