Papers about retroduplications (variable pseudogenes)
here are three more relevant papers about retroduplications :
http://www.nature.com/nmeth/journal/v9/n2/full/nmeth.1810.html http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1003242 http://genomebiology.com/content/14/3/R22