Vinyl sheath, a cover for "Musigraph 100", music theory slide rule
Vinyl sheath, a cover for 'Musigraph 100', slide rule for music theory, by Musigraph Company, Teaneck, New Jersey, United States of America, 1985
Vinyl sheath, a cover for 'Musigraph 100', slide rule for music theory, by Musigraph Company, Teaneck, New Jersey, United States of America, 1985