DeFries-Fulker analysis of longitudinal reading performance data from twin pairs ascertained for reading difficulties and from their nontwin siblings.
Astrom RL, Wadsworth SJ, Olson RK, Willcutt EG, DeFries JC. DeFries-Fulker analysis of longitudinal reading performance data from twin pairs ascertained for reading difficulties and from their nontwin siblings. Behav Genet. 2011 Sep; 41(5):660-7.