1. Kemendikbud. Surat Edaran Pelaksanaan Kebijakan Pendidikan dalam Masa Darurat Penyebaran Coronavirus Disease (Covid-19) [Circular Letter on the Implementation of Education Policy in the Emergency Period of the Spread of Coronavirus Disease] (16 August 2020).
2. J. L. Villegas, E. Castro, and J. Gutiérrez, Electronic Journal of Research Education Psychology 7, 279–308 (2009).
3. Flexible and adaptive use of strategies and representations in mathematics education
4. Solution representations and pedagogical representations in Chinese and U.S. classrooms
5. Symbolic and Verbal Representation Process of Student in Solving Mathematics Problem Based Polya’s Stages