Hasbi, Maude (1 September 2014). "Universal Service Obligations and Public Payphone Use: Is Regulation Still Necessary in the Era of Mobile Telephony?". doi:10.2139/ssrn.2499391. SSRN2499391. {{cite web}}: Missing or empty |url= (help)
Hasbi, Maude (1 September 2014). "Universal Service Obligations and Public Payphone Use: Is Regulation Still Necessary in the Era of Mobile Telephony?". doi:10.2139/ssrn.2499391. SSRN2499391. {{cite web}}: Missing or empty |url= (help)