Birdsong, D. (1999). Second language acquisition and the critical period hypothesis. Lawrence Erlbaum Associates.
Dyfyniad Arddull ChicagoBirdsong, David. Second Language Acquisition and the Critical Period Hypothesis. Mahwah: Lawrence Erlbaum Associates, 1999.
Dyfyniad MLABirdsong, David. Second Language Acquisition and the Critical Period Hypothesis. Lawrence Erlbaum Associates, 1999.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.