References
- Bernfeld , S.R. , Lakshmikantham , V. and Reddy , Y. M . 1977 . “Fixed point theorems of operators with PPF dependence in Banach spaces,” . Appl. Analysis , 6 : 270 – 280 .
- Ludde , G. S. , Lakshmikantham , V. and Vatsala , A. S. Monotone iterative technilogy for nonlinear differential equations , Pitman Publishing, Ltd .
- Lakshmikantham, V., “Periodic boundary value problems of first and second order differential equations, Lakshmikantham, V., ”Periodic boundary value problems of first and second order differential equations, ” to appear. to appear