1.
Utama J, Handoko Y, Saefulloh C. Design of an Electrocardiogram System for Physical Fitness Analysis using Heart Rate Variability and Maximal Oxygen Volume. IJIES [Internet]. 2025 Nov. 5 [cited 2026 Jan. 13];9(2):134-50. Available from: https://journals.telkomuniversity.ac.id/ijies/article/view/9790