Sulma Hajijatur Ridlwana; Arifiani Agustin Amalia; Yeni Rahmawati. Internal Quality Control Analysis of Sgot and Sgpt Examination Using Levey-Jennings Graphics and Six Sigma at X Hospital Yogyakarta: Analisis Quality Control Internal Pemeriksaan Sgot Dan Sgpt Menggunakan Grafik Levey-Jennings Dan Six Sigma Di RS X Yogyakarta. JoH 2025, 12, 060-068.