Maksimović, Jelena, and Sanja Sretić. “ Principle of Evidence of John Amos Comenius As a Basis for the Development of Pedagogical Research Techniques and Instruments”. Siedleckie Zeszyty Komeniologiczne Seria Pedagogika, vol. 6, Dec. 2019, pp. 243-56, https://czasopisma.uph.edu.pl/szk/article/view/1492.