Gunawan, I., Kusumaningrum, D.E., Triwiyanto, T., Zulkarnain, W., Nurabadi, A., Sanutra, M.F.A., Rosallina, N.S., Rofiq, M.A., Afiantari, F., & Supriyanto, K.P. (2018). Hidden curriculum and character building on self-motivation based on k-means clustering. 2018 4th International Conference on Education and Technology (ICET), pp. 32-35. IEEE.