SOTYANINGRUM, Alfra Tien. Kesalahan-Kesalahan Penulisan Surat. Efisiensi : Kajian Ilmu Administrasi, [S. l.], v. 12, n. 1, 2015. DOI: 10.21831/efisiensi.v12i1.3867. Disponível em: https://journal.uny.ac.id/index.php/efisiensi/article/view/3867. Acesso em: 12 may. 2025.