Knowlton sold the bindery to Eric Zimmerman and Richard Frieder. Frieder later sold his portion of the business to Eric and Kenda Zimmerman who moved it to Foster RI and operated it for many years. Knowlton retired from Brown University in 1992. He continued to work and teach bookbinding part-time at his Longfield Studio in Bristol until 2014. He died in 2015, aged 92. References 1922 births American people with disabilities Bookbinders 2015 deaths People from Bristol, Rhode Island People from Washington, D.C. Brown University staff