Submitted on: 20 August 2014.
Revised on: 10 December 2014.
Accepted on: 24 January 2015.
___________________Electronic Journal of Differential Equations
Submitted on: 31 January 2005.
Revised on: 03 May 2005.
Accepted on: 26 June 2005.
___________________Electronic Journal of Differential Equations
Submitted on: 15 August 1998.
Revised on: 22 September 1998.
Accepted on: 16 October 1998.
___________________Electronic Journal of Differential Equations
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Submitted on: 06 June 2006.
Revised on: 29 July 2006.
Accepted on: 23 August 2006.
___________________Electronic Journal of Differential Equations
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Submitted on: 07 March 2001.
Revised on: 02 June 2001.
Accepted on: 15 July 2001.
___________________Electronic Journal of Differential Equations
Submitted on: 06 April 2003.
Revised on: 28 June 2003.
Accepted on: 04 August 2003.
___________________Electronic Journal of Differential Equations