Kerta, Johan Muliadi, et al. “Analisis Dan Perancangan Sistem Interactive Voice Response (IVR) Berbasis Openvxi Menggunakan Asterisk Pada Hotel Sahid Jaya”. ComTech: Computer, Mathematics and Engineering Applications, vol. 1, no. 2, Dec. 2010, pp. 723-36, doi:10.21512/comtech.v1i2.2573.