1. Davydov, V. V. (1990). Types of generalization in instruction. Reston, VA: National Council of Teachers of Mathematics
2. Vygotsky, L. S. (1982). Emotsii i ikh razvitije v detskom vozraste [Emotions and emotional development of children]. In V. V. Davydov (Ed.), Sobranije Sochinenij [Selected works], Vol. 2 (pp. 416–436). Moscow: Pedagogika
3. The Origin and Development of Cognitive Abilities in Preschool Children
4. Vygotsky, L. S. (1984). Voprosy detskoy (vozrastnoy) psychologii [Issues in child (developmental) psychology]. In D. B. Elkonin (Ed.), Sobranije Sochinenij [Selected works], Vol. 4 (pp. 244–385). Moscow: Pedagogika
5. Elkonin, D. (1978). Psychologija igry [The psychology of play]. Moscow: Pedagogika