RT Journal Article SR Electronic A1 Jůvová, Alena A1 Bakker, Froukje T1 Didactic Principles by Comenius and 21st Century Skills JF e-Pedagogium YR 2015 VO 15 IS 2 SP 7 OP 20 DO 10.5507/epd.2015.013 UL https://e-pedagogium.upol.cz/en/artkey/epd-201502-0002.php AB