1. ADL: GitHub - adlnet/xAPI-Spec, https://github.com/adlnet/xAPI-Spec
2. ADL: xAPI-Spec/xAPI-Communication.md at master · adlnet/xAPI-Spec · GitHub, https://github.com/adlnet/xAPI-Spec/blob/master/xAPI-Communication.md#stmtresget
3. Bakharia A xAPI Analytics - Stepping out of the LRS (Part 1), http://www.beyondlms.org/blog/27/07/2015/xAPISteppingOutoftheLRS/
4. Bakharia A, Kitto K, Pardo A, Gaševi D, Dawson S Recipe for Success — Lessons Learnt from Using xAPI within the Connected Learning Analytics Toolkit
5. Berning, M., Yonezawa, T., Riedel, T., Nakazawa, J., Beigl, M., Tokuda, H (2013) pARnorama. In: Proceedings of the 2013 ACM conference on Pervasive and ubiquitous computing adjunct publication - UbiComp ‘13 Adjunct. ACM Press, New York, New York, USA, p 1471–1474