參考資料
[1] 盛驟, 謝式千, 潘承毅. 概率論和數理統計[J]. 2001.
[2] https://en.wikipedia.org/wiki/Maximum_likelihood
[3] https://www.youtube.com/watch?v=fvNUUJuFXM0
[4] https://en.wikipedia.org/wiki/Independent_and_identically_distributed_random_variables
[5] http://www.cnblogs.com/liliu/archive/2010/11/22/1883702.html