Submitted on: 28 November 2011.
Revised on: 07 January 2012.
Accepted on: 12 January 2012.
Mathematica Bohemica---INST MATHEMATICS, AS CR
Submitted on: 08 February 2014.
Revised on: 19 February 2014.
Accepted on: 01 March 2014.
Mathematica Bohemica
http://reply.papertrans.cn/3/215/21419/21419-13.png
http://reply.papertrans.cn/3/215/21419/21419-14.png
http://reply.papertrans.cn/3/215/21419/21419-15.png
http://reply.papertrans.cn/3/215/21419/21419-16.png
Submitted on: 27 August 2007.
Revised on: 16 September 2007.
Accepted on: 25 September 2007.
Mathematica Bohemica
http://reply.papertrans.cn/3/215/21419/21419-18.png
Submitted on: 15 June 2011.
Revised on: 18 July 2011.
Accepted on: 28 July 2011.
Mathematica Bohemica---INST MATHEMATICS, AS CR
Submitted on: 02 December 2013.
Revised on: 20 December 2013.
Accepted on: 17 January 2014.
Mathematica Bohemica