Hardy, W. C. (2003). VoIP Service qualityMeasuring and evaluating packet-switched voiceWilliam C. Hardy. McGraw-Hill.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रHardy, William C. VoIP Service QualityMeasuring and Evaluating Packet-switched VoiceWilliam C. Hardy. McGraw-Hill, 2003.
एमएलए (8वां संस्करण) प्रशस्ति पत्रHardy, William C. VoIP Service QualityMeasuring and Evaluating Packet-switched VoiceWilliam C. Hardy. McGraw-Hill, 2003.
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