Lelawarna, L. “Effort Increasing Learning Result Of Communication Operations Calculating Methods Using Napier Bone Students Class Students In Basic Schools 12 Tebat Karai”. Jurnal PGSD: Jurnal Ilmiah Pendidikan Guru Sekolah Dasar, vol. 11, no. 2, Dec. 2018, pp. 112-9, doi:10.33369/pgsd.11.2.112-119.