sentences:  Initially called Serendipity Books Distribution, it was renamed Small Press Distribution by the late 1970s.Throughout the 1970s and 1980s, the organization periodically assembled the new titles of their publishers into printed catalogs, thus providing a vital link to underground literature for writers and readers around the US.By 1980, SPD was distributing the books of about 40 small publishers; by 1990, the number had grown to 330.