When did the person Kosti Vehanen spend a decade accompanying die?
Kosti Vehanen:  In addition, Vehanen also penned several memoirs, including 1941 book chronicling his decade long experience serving as Marian Anderson's accompanist. Marian Anderson: Marian Anderson (February 27, 1897 – April 8, 1993) was an African-American contralto and one of the most celebrated singers of the twentieth century.
April 8, 1993