http://reply.papertrans.cn/3/250/24916/24916-21.png
Submitted on: 17 June 1998.
Revised on: 04 July 1998.
Accepted on: 23 July 1998.
NULL
Submitted on: 27 March 2021.
Revised on: 18 April 2021.
Accepted on: 14 May 2021.
PNA-Revista de Investigacion en Didactica de la Matematica
Submitted on: 05 August 1999.
Revised on: 14 September 1999.
Accepted on: 04 October 1999.
NULL
http://reply.papertrans.cn/3/250/24916/24916-25.png
http://reply.papertrans.cn/3/250/24916/24916-26.png
Submitted on: 14 April 2021.
Revised on: 22 May 2021.
Accepted on: 28 May 2021.
NULL
http://reply.papertrans.cn/3/250/24916/24916-28.png
http://reply.papertrans.cn/3/250/24916/24916-29.png
Submitted on: 24 July 2007.
Revised on: 10 August 2007.
Accepted on: 31 August 2007.
NULL