I. Hardianto, I. Wiryokusumo, and D. A. Walujo, “Developing Non-Fiction Book on Animal Characteristics to Stimulate Cognitive Development of Early Childhood”, Int J Innov Educ Res, vol. 6, no. 12, pp. 255–268, Dec. 2018, doi: 10.31686/ijier.vol6.iss12.1275.