Pratama, A.Y., Perdana, M.W. and Jimmie, J. 2025. Rancang Bangun Smart Doorbell Menggunakan Sensor Ultrasonik HC-SR04 Berbasis IoT. SENTRI: Jurnal Riset Ilmiah. 4, 11 (Nov. 2025), 3090–3101. DOI:https://doi.org/10.55681/sentri.v4i11.5028.