Chukharev-Hudilainen, Evgeny, and Tatiana A. Klepikova. “The Effectiveness of Computer-Based Spaced Repetition in Foreign Language Vocabulary Instruction: A Double-Blind Study”. CALICO Journal, vol. 33, no. 3, Aug. 2016, pp. 334–354, https://doi.org/10.1558/cj.v33i3.26055.