<a class="mw-redirect" href="https://en.wikipedia.org/wiki/ZIP_code" id="mwAbI" rel="mw:WikiLink" title="ZIP code">ZIP codes</a> are introduced for <a href="https://en.wikipedia.org/wiki/United_States_Postal_Service" id="mwAbM" rel="mw:WikiLink" title="United States Postal Service">United States mail</a>.<sup about="#mwt114" class="mw-ref reference" data-mw='{"name":"ref","attrs":{},"body":{"id":"mw-reference-text-cite_note-19"}}' id="cite_ref-19" rel="dc:references" typeof="mw:Extension/ref"><a href="./July_1#cite_note-19" id="mwAbQ" style="counter-reset: mw-Ref 19;"><span class="mw-reflink-text" id="mwAbU">[19]</span></a></sup>
<span class="mw-reference-text" id="mw-reference-text-cite_note-19"><cite about="#mwt111" class="citation book cs1" id="CITEREFJaneczko2004">Janeczko, Paul B. (2004). <a class="external text" href="https://books.google.com/books?id=_HjRUYwJ1moC" id="mwCWo" rel="mw:ExtLink nofollow"><i id="mwCWs">Top Secret: A Handbook of Codes, Ciphers, and Secret Writing</i></a>. Cambridge, Mass.: Candlewick Press. p.<span id="mwCWw" typeof="mw:Entity"> </span>8. <a class="mw-redirect" href="./ISBN_(identifier)" id="mwCW0" rel="mw:WikiLink" title="ISBN (identifier)">ISBN</a><span id="mwCW4" typeof="mw:Entity"> </span><a href="./Special:BookSources/9780763629724" id="mwCW8" rel="mw:WikiLink" title="Special:BookSources/9780763629724"><bdi id="mwCXA">9780763629724</bdi></a>.</cite><span about="#mwt111" class="Z3988" id="mwCXE" title="ctx_ver=Z39.88-2004&amp;rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&amp;rft.genre=book&amp;rft.btitle=Top+Secret%3A+A+Handbook+of+Codes%2C+Ciphers%2C+and+Secret+Writing&amp;rft.place=Cambridge%2C+Mass.&amp;rft.pages=8&amp;rft.pub=Candlewick+Press&amp;rft.date=2004&amp;rft.isbn=9780763629724&amp;rft.aulast=Janeczko&amp;rft.aufirst=Paul+B.&amp;rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3D_HjRUYwJ1moC&amp;rfr_id=info%3Asid%2Fen.wikipedia.org%3AJuly+1"></span></span>