Nakata, Tatsuya. “Implementing Optimal Spaced Learning for English Vocabulary Learning: Towards Improvement of the Low-First Method Derived from the Reactivation Theory”. The JALT CALL Journal 2, no. 2 (August 31, 2006): 19–36. Accessed September 22, 2026. https://www.castledown.com.au/journals/jaltcall/article/view/jaltcall.v2n2.24.