I suggest you look
here for more info about using L2 language in the classroom.
The references included in the article are below:
Atkinson, D. 1987. 'The mother-tongue in the classroom : a neglected resource ?' (ELT Journal, 44/1 : 3-10)
Atkinson, D. 1993. Teaching Monolingual Classes (Longman)
Baynham, M. 1983. 'Mother Tongue Materials and Second Language Literacy' (ELT Journal, 37/4 : 312-318)
Brumfit, C. 1980. Problems and principles in English Teaching. (Pergamon)
Duff. A. 1989. Translation (Oxford University Press)
Kramsch, C. 1993. Context and Culture in Language Teaching (Oxford University Press)
Kramsch, C. 1998. Culture (Oxford University Press)
Krashen, S. 1988. Second Language Acquisition and Second Language Learning (Prentice Hall)
Medgyes, P. 1994. The Non-Native Teacher ( Macmillan)
Phillipson, R. 1992. Linguistic Imperialism (Oxford University Press)
Richards, J.C. and T. S. Rogers. 1986. Approaches and Methods in Language Teaching. (Cambridge University Press)
Widdowson, H 1996. 'Comment : authenticity and autonomy' E L T Journal, 50/1: 67-68))