van der Slik, F. W. P., van Hout, R. W. N. M., & Schepens, J. J. (2015). The gender gap in second language acquisition: Gender differences in the acquisition of Dutch among immigrants from 88 countries with 49 mother tongues. PLoS ONE, 10(11): e0142056. doi:10.1371/journal.pone.0142056.