TY - JOUR AU - Cepeda, N J; Vul, E; Rohrer, D; Wixted, J T; Pashler, H TI - Spacing effects in learning: a temporal ridgeline of optimal retention JO - Psychol Sci IS - 11 VL - 19 PY - 2008 DO - 10.1111/j.1467-9280.2008.02209.x L3 - PubMed-ID: 19076480 SP - 1095 EP - 1102 ER -