1. Bravo, M.C.M., Chalezquer, C.S., Serrano-Puche, J. Meta-framework of digital literacy: Comparative analysis of 21st century skills frameworks. Rev Lat Comun Soc. 2021;2021(79).
2. González-salamanca, J.C., Agudelo, O.L., Salinas, J. Key competences, education for sustainable development and strategies for the development of 21st century skills. A systematic literature review. Sustain. 2020;12(24).
3. Jedaman, P., Kenaphoom, S., Jongmuanwai, B., Niyomves, B. Analyzed and Causal Factor the 21st Century Leadership 4.0 of Science Educational for Sustainable. In: Journal of Physics: Conference Series. 2021.
4. Rochmawati, A., Ridlo, S. Analysis of 21 st Century Skills of Student on Implementation Project Based Learning and Problem Posing Models in Science Learning. J Prim Educ. 2020;9(1).
5. Maftukhatul, K., Sigit, S. Application of Flipped Learning in Online Learning on the Effects of the Covid-19 Pandemic in Increasing Learner Motivation. UNNES Semarang. proceeding.unnes.ac.id; 2020.