Wardani, Danti Ayu, et al. “Development of Assessment Instruments in Project-Based Learning to Measure Collaboration Skills and Compassion for Students in Elementary School”. The International Journal of Social Sciences World (TIJOSSW), vol. 3, no. 1, June 2021, pp. 218-27, https://www.growingscholar.org/journal/index.php/TIJOSSW/article/view/116.