Employees at HarperCollins Publishers launched an open-ended strike Thursday amid stalled contract negotiations. Workers are demanding HarperCollins increase pay and provide better paid leave benefits, as well as address its lack of diversity. HarperCollins is the publisher of Howard Zinn’s “A People’s History of the United States,” as well as the books “A Collective Bargain: Unions, Organizing, and the Fight for Democracy” and “Squeezed: Why Our Families Can’t Afford America.”