http://reply.papertrans.cn/1/98/9750/9750-21.png
Submitted on: 15 January 2018.
Revised on: 15 March 2018.
Accepted on: 02 April 2018.
___________________Filomat---UNIV NIS, FAC SCI MATH
Submitted on: 03 August 2007.
Revised on: 28 September 2007.
Accepted on: 08 November 2007.
___________________Filomat---UNIV NIS, FAC SCI MATH
http://reply.papertrans.cn/1/98/9750/9750-24.png
Submitted on: 26 May 2017.
Revised on: 19 September 2017.
Accepted on: 16 November 2017.
___________________Filomat---UNIV NIS, FAC SCI MATH
Submitted on: 11 October 2001.
Revised on: 17 November 2001.
Accepted on: 28 December 2001.
___________________Filomat---UNIV NIS, FAC SCI MATH
http://reply.papertrans.cn/1/98/9750/9750-27.png
Submitted on: 31 December 2017.
Revised on: 19 March 2018.
Accepted on: 02 April 2018.
___________________Filomat---UNIV NIS, FAC SCI MATH
Submitted on: 12 March 2003.
Revised on: 16 May 2003.
Accepted on: 30 May 2003.
___________________Filomat---UNIV NIS, FAC SCI MATH
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