Salsabella, Ainun, and Titin Aryani. 2022. “Sigma Matrix of Ureum and Creatinine in Some Laboratories: Overview: Gambaran Matrik Sigma Pemeriksaan Ureum Dan Kreatinin Pada Beberapa Laboratorium”. Medicra (Journal of Medical Laboratory Science Technology) 5 (1):40-46. https://doi.org/10.21070/medicra.v5i1.1628.