U. Khofifah, J. Ratnasari, and A. Juhanda, “Analisis Butir Soal Kemampuan Tree Thinking Pada Instrumen Uji Coba Materi Spermathophyta: (Analysis of tree thinking ability problem ability in spermathophyta trial material instruments)”, Biodik , vol. 6, no. 3, pp. 332-342, Oct. 2020.