http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.2006.00099.x/full
http://jhered.oxfordjournals.org/content/95/1/19.short
http://www.bioone.org/doi/abs/10.2981/0909-6396(2007)13%5B38:EFMDIB%5D2.0.CO%3B2
http://onlinelibrary.wiley.com/doi/10.1111/j.1471-8286.2005.00936.x/full
http://gradworks.umi.com/33/58/3358688.html
http://link.springer.com/article/10.1023/B:COGE.0000031141.47148.8b
http://www.bioone.org/doi/abs/10.1674/0003-0031(2008)159%5B504:CLLCLR%5D2.0.CO%3B2