1. Adler-kassner, L., Majewski, J., & Koshnick, D. (2012). The value of troublesome knowledge: Transfer and threshold concepts in writing and history. Composition Forum, 26(Fall), 1–17.
2. Atherton, J. S., Hadfield, P., & Meyers, R. (2008). Threshold concepts in the wild. Practice, (June), 1–13. Retrieved from http://www.doceo.co.uk/tools/Threshold_Concepts_Wild_expanded_70.pdf
3. Bradbeer, J. (2005). Threshold concepts and troublesome knowledge in the GEES disciplines. Planet, 15(3). Retrieved from http://dx.doi.org/10.11120/plan.2005.00150003
4. Cousin, G. (2006). Section 1: An introduction to threshold concepts. Planet, 17, 4–5. doi:10.11120/ plan.2006.00170004
5. Davies, P., & Mangan, J. (2005, August 23–27). Recognising threshold concepts: An exploration of different approaches. Paper presented at the European Association in Learning and Instruction