Submitted on: 26 February 2000.
Revised on: 16 March 2000.
Accepted on: 04 April 2000.
NULL
http://reply.papertrans.cn/3/244/24303/24303-32.png
Submitted on: 05 November 2018.
Revised on: 29 November 2018.
Accepted on: 11 December 2018.
Perspectiva Educacional---EDICIONES UNIV VALPARAISO
Submitted on: 24 November 2022.
Revised on: 22 December 2022.
Accepted on: 19 January 2023.
NULL
http://reply.papertrans.cn/3/244/24303/24303-35.png
Submitted on: 12 March 2009.
Revised on: 06 April 2009.
Accepted on: 13 April 2009.
NULL