I use google sources, however I got surprise today that I went to test my files in firefox and realized that the font was not loaded. See
@font-face {
font-family: 'Bree Serif';
font-style: normal;
font-weight: 400;
src: local('Bree Serif'), local('BreeSerif-Regular'), url(http://fonts.gstatic.com/s/breeserif/v5/0daoUMW28nkWOnFz2G4AAgsYbbCjybiHxArTLjt7FRU.woff2) format('woff2');
unicode-range: U+0100-024F, U+1E00-1EFF, U+20A0-20AB, U+20AD-20CF, U+2C60-2C7F, U+A720-A7FF;
}
@font-face {
font-family: 'Bree Serif';
font-style: normal;
font-weight: 400;
src: local('Bree Serif'), local('BreeSerif-Regular'), url(http://fonts.gstatic.com/s/breeserif/v5/LQ7WLTaITDg4OSRuOZCpswsYbbCjybiHxArTLjt7FRU.woff2) format('woff2');
unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2212, U+2215, U+E0FF, U+EFFD, U+F000;
}
div {
font-family: 'Bree Serif';
}