Lumban Raja, S. E. “Peningkatan Penguasaan Vocabulary Terkait Singular and Plural Noun Melalui Crossword and Puzzle Game Pada Siswa Kelas VIII SMP”. Journal of Education Action Research, vol. 5, no. 4, Dec. 2021, pp. 515-20, doi:10.23887/jear.v5i4.12336.