1. K. Daryanto and D. S. Karim, Pembelajaran Abad 21 (Gava Media, Yogyakarta, 2017).
2. T. Bramley, S. Child, J. Munro, and T. Benton, This is a single article from Research Matters: A Cambridge Assessment publication. http://www. cambridgeassessment.org.uk/research-matters/© UCLES 2018. (2018).
3. A. M. Fanny, Jurnal Pendidikan Dasar 10 (2), pp. 44–52 (2019).
4. Efektivitas Model Pembelajaran CUPs: Dampak Terhadap Kemampuan Berpikir Tingkat Tinggi Peserta Didik Madrasah Aliyah Mathla’ul Anwar Gisting Lampung
5. H. N. Dinni, in PRISMA Prosiding Seminar Nasional Matematika, edited by I. Rosyida et al. (FMIPA Unnes, Semarang 2018), pp. 170–176.