Cited References

Cepeda, N. J., Vul, E., Rohrer, D., Wixted, J. T., & Pashler, H.. (2008). Spacing effects in learning: a temporal ridgeline of optimal retention. Psychological Science: A Journal of the American Psychological Society / APS, 19(11), 1095 - 1102. presented at the 2008/11//. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/19076480