A Scale for Measuring the Relative Difficulty of High-School Subjects

Autor:	Osborn, L. G.
Zdroj:	The Journal of Educational Research, 1939 Sep 01. 33(1), 1-6.
Databáze:	JSTOR Journals
Externí odkaz:	https://www.jstor.org/stable/27526623 Zobrazit plný text záznamu