Nakata T. Implementing optimal spaced learning for English vocabulary learning: Towards improvement of the low-first method derived from the reactivation theory. JALTCALL [Internet]. 2006 Aug. 31 [cited 2026 Sep. 22];2(2):19-36. Available from: https://www.castledown.com.au/journals/jaltcall/article/view/jaltcall.v2n2.24