Kharis, M., K. Laksono, Suhartono, A. Ridwan, Mintowati, and Yuniseffendri. “Tokenization and Lemmatization on German Learning Textbook Level A1 of CEFR Standard”. Journal of Higher Education Theory and Practice, vol. 22, no. 1, Feb. 2022, doi:10.33423/jhetp.v22i1.4971.