Complex sentence: Carlos Guastavino (April 5,1912-October 29,2000) was one of the foremost Argentine composers of the 20th century, his production amounted to over 500 works, most of them songs for piano and voice, many still unpublished.
Split into simpler sentences: Carlos Guastavino (April 5,1912-October 29,2000) was one of the foremost Argentine composers of the 20th century. His production amounted to over 500 works, most of them songs for piano and voice, many still unpublished.