http://reply.papertrans.cn/1/53/5217/5217-21.png
http://reply.papertrans.cn/1/53/5217/5217-22.png
Submitted on: 16 August 2006.
Revised on: 20 October 2006.
Accepted on: 18 November 2006.
___________________Child Indicators Research---SPRINGER
Submitted on: 27 June 2019.
Revised on: 25 August 2019.
Accepted on: 17 October 2019.
___________________Child Indicators Research---SPRINGER
http://reply.papertrans.cn/1/53/5217/5217-25.png
Submitted on: 27 June 2023.
Revised on: 09 October 2023.
Accepted on: 08 November 2023.
___________________Child Indicators Research---SPRINGER
http://reply.papertrans.cn/1/53/5217/5217-27.png
http://reply.papertrans.cn/1/53/5217/5217-28.png
http://reply.papertrans.cn/1/53/5217/5217-29.png
http://reply.papertrans.cn/1/53/5217/5217-30.png