RT Article T1 Genetic and environmental covariance among WISC-R subtests: a study JF Intelligence VO 11 IS 3 SP 233 OP 245 A1 LaBuda, Michele C. A2 DeFries, John C. 1934- A2 Fulker, David W. LA English YR 1987 UL https://krimdok.uni-tuebingen.de/Record/163799124X K1 Zwillingsforschung