SANTOS, Ma. Arra B.. Biology Teachers' Systems Thinking Practices and Students' 21st Century Skills: Bases for A Professional Development Model. Philippine Journal of Education Studies (formerly the Education Quarterly), [S.l.], v. 2, n. 2, p. 95-126, aug. 2025. ISSN 2984-8180. Available at: <https://journals.upd.edu.ph/index.php/pjes/article/view/10773>. Date accessed: 02 sep. 2025.