How to include Bootstrap source files (Glyphicons) in Rails?

In my Rails applications I usually include Bootstrap manually in folders:

• app/assets/stylesheets/lib (CSS) and
• app/assets/javascripts/lib (Javascript)

Everything works perfectly except for Glyphicons .

I put the font files in the app/assets/fonts folder but it does not recognize them. HTML <span class="glyphicon glyphicon-search"></span> generates the following symbol:

BelowtheFirefoxconsoleprint:

Here is the snippet that contains the URLs (unchanged):

@font-face {
  font-family: 'Glyphicons Halflings';

  src: url('../fonts/glyphicons-halflings-regular.eot');
  src: url('../fonts/glyphicons-halflings-regular.eot?#iefix') format('embedded-opentype'), url('../fonts/glyphicons-halflings-regular.woff') format('woff'), url('../fonts/glyphicons-halflings-regular.ttf') format('truetype'), url('../fonts/glyphicons-halflings-regular.svg#glyphicons_halflingsregular') format('svg');
}