http://reply.papertrans.cn/3/276/27503/27503-31.png
http://reply.papertrans.cn/3/276/27503/27503-32.png
Submitted on: 19 November 2009.
Revised on: 30 November 2009.
Accepted on: 13 December 2009.
Scandinavian Actuarial Journal
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http://reply.papertrans.cn/3/276/27503/27503-35.png
Submitted on: 15 May 2022.
Revised on: 10 June 2022.
Accepted on: 28 June 2022.
Scandinavian Actuarial Journal