BISG Executive Director to Resign; Vlahos to Tattered Cover; New Executive Sought Contact: Jeanette Zwart  BISG | 145 West 45th St. Suite 601 | New York NY | 10036 646.336.7141 ext. 11 | jeanette@bisg.org | www.bisg.org   (New York, NY: March 26, 2015) The Book Industry Study Group (BISG) announced today that Executive Director Len Vlahos will resign his position effective June 12, and will relocate to Denver, Colorado where he and his wife will join the senior management team of the Tattered Cover bookstores and will eventually acquire a…