1. S.E. Ashoo, T. Boudreau, D.A. Lane, Programming Contest Control System, http://www.ecs.csus.edu/pc2/ (Accessed: June 07.06.16).
2. M. Bayer, The Python SQL Toolkit and Object Relational Mapper, http://www.sqlalchemy.org/ (Accessed: 07.06.16).
3. J. Breitner, M. Hecker, Quality control for programming assignments, https://github.com/KITPraktomatTeam/Praktomat/ (Accessed: June 07.06.16).
4. Cloud9, Online Code Editor, https://c9.io (Accessed: 07.06.16).
5. Eclipse Che, Eclipse IDE Cloud Service, https://eclipse.org/che/ (Accessed: 07.06.16).