++ abreviations

doc/refs/refs.bib

@@ -4,3 +4,21 @@
     PUBLISHER = "Addison-Wesley Publishing Company",
     ADDRESS = "Reading, Massachusetts",
     YEAR = "1986"}
+
+@Misc{ripe_exhaustion,
+  author =    {RIPE},
+  howpublished = {\url{https://www.ripe.net/publications/ipv6-info-centre/about-ipv6/ipv4-exhaustion}}}
+
+@Misc{apnic_exhaustion,
+  author =    {APNIC},
+  howpublished = {\url{https://www.apnic.net/community/ipv4-exhaustion/graphical-information/}}}
+
+@Misc{google:_ipv6_googl,
+  author =    {Google},
+  title =     {IPv6 - Google},
+  howpublished = {\url{https://www.google.com/intl/en/ipv6/statistics.html}}}
+
+@Misc{lacnic:_ipv4_deplet_phases,
+  author =    {LACNIC},
+  title =     {IPv4 Depletion Phases},
+  howpublished = {\url{https://www.lacnic.net/1039/1/lacnic/ipv4-depletion-phases}}}