Hi Mehdi, here are a few good sources:

http://www.paduan.dk/Kunsthistorie%202008/Tekster/CLEMENT%20GREENBERG-AVANT-GARDE%20AND%20KITSCH.pdf this one argues that kitsch is a legitimate designation.

Pierre Bourdieu's 'Distinction' particularly section III.

Susan Sontag's One culture and the new sensibility, which acknowledges the existence of high and low culture, but also shows that they are dissolving.

Kitsch: history, theory, practice (if you can get your hands on it, this is basically all you'd need)

Beautiful kitsch by Tiffany D.E. Yonts, which discusses the tolerance of Kitsch among the educated. it may be a good idea to read this alongside the Bourdieu.

Good luck with your research!