S. T. Madawistama, Y. Heryani, and D. Kurniawan, “Three zone learning concepts to improve mathematical proof of probability theory”, J. Math Educ. Nusant. Wahana Publ. Karya Tulis Ilm. di Bid. Pendidik. Mat., vol. 8, no. 1, pp. 27-38, May 2022.