see <#bep=Bureau of Engraving and Printing>.

see <#bia=Bureau Issues Association>.

see <#bob=Back of the Book>.

a nick name for 1933 50¢ Century of Progress Flight <#airmail=air mail> <#poststamp=postage stamp>, which portrays the Graf Zeppelin.  <#scott=Scott> C18.

items listed in <#scott=Scott Catalogue> following <#poststamp=Postage Stamps>, which begin their Scott number with a letter prefix.  For example, catalogue numbers for <#amstamp=Air Mail Stamps> are prefixed with "C" and those for <#revenue=revenue stamps> are prefixed with "R".