1. Albertsen, N., & Diken, B. (2003) - What is the Social? Dep. of Sociology, Lancaster University (http://www.comp.lancs.ac.uk/sociology/papers/albertsen-diken-what-is-the-social.pdf)
2. Avramov, R. (1996), The ‘Cooperative Movement’ in Early 20th Century Bulgaria,” in: Sociological Problems 1996, Vol.4, p.97 (in Bulgarian)
3. Belogusheva, G. and Justin Toms (2003). The First in The Bulgarian Internet, CIELA, Sofia (in Bulgarian), pp.23-25