What is IGRA? The International Guitar Research Archive What is IGRA? The International Guitar Research Archive (IGRA) is one of the world’s largest collections of guitar sheet music. Housed here are works for solo guitar, as well as ensemble pieces for multiple guitars and other instruments. There is a variety of music, some of it rare and unique. The majority of the sheet music comes from the Vahdah Olcott-Bickford Estate, providing the foundation for the Archive. In the following years, IGRA received collections from the Laurindo Almeida Estate, Vicente Gomez, Clarence Easley, Christopher Parkening, Robert Strizich, John Tanno, Angelo Gillardino, and Neil Anderson. IGRA’s founder, Ron Purcell, has donated his personal collection as well. In addition to Ms.