...Wikipedia text is available under Creative Commons Attribution-ShareAlike 3.0 License. https://en.wikipedia.org/wiki/Wikipedia:About
To cite the corpora:
M. Saad, D. Langlois, and K. Smaïli. Extracting Comparable Articles from Wikipedia and Measuring their Comparabilities. Procedia - Social and Behavioral Sciences, 95(0):40 – 47, 2013. ISSN 1877-0428.