Day, E. J. (1932). The development of language in twins: II. The development of twins: their resemblances and differences. Child Development, 3(4), 298-316. [FULLTEXT]
A History of Psycholinguistics
Bibliography for Levelt (2013)

Day, E. J. (1932). The development of language in twins: II. The development of twins: their resemblances and differences. Child Development, 3(4), 298-316. [FULLTEXT]