Submitted on: 27 June 2017.
Revised on: 26 July 2017.
Accepted on: 31 July 2017.
Kragujevac Journal of Mathematics
Submitted on: 09 February 2011.
Revised on: 24 March 2011.
Accepted on: 16 April 2011.
Kragujevac Journal of Mathematics
Submitted on: 23 February 2014.
Revised on: 27 March 2014.
Accepted on: 22 April 2014.
Kragujevac Journal of Mathematics
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Submitted on: 27 January 2017.
Revised on: 10 February 2017.
Accepted on: 04 March 2017.
Kragujevac Journal of Mathematics
Submitted on: 15 June 2000.
Revised on: 21 July 2000.
Accepted on: 13 August 2000.
Kragujevac Journal of Mathematics
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Submitted on: 12 February 2012.
Revised on: 18 March 2012.
Accepted on: 29 March 2012.
Kragujevac Journal of Mathematics
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