Tampubolon, Taruly, and Dr. Robert Harianja. “The Implementation of Guilford Learning Production Dimensions in Ninth Grade Students of SMP Negeri I Sipahutar Tapanuli Utara”. International Journal of Humanities and Education Development (IJHED), vol. 2, no. 5, Oct. 2020, pp. 350-4, https://doi.org/10.22161/.