Alam, M. S., and M. R. H. Khan. “Message Based Analysis on Signaling System Number 7 and Its Comparison With Multi-Frequency Coded Signaling”. Daffodil International University Journal of Science and Technology, vol. 7, no. 1, Jan. 2012, pp. 15-19, doi:10.3329/diujst.v7i1.9582.