Includes letters to Spiegelberg from: Douglas Steere, J. Harry Cotton; Professor, Wabash College; Harry T. Costello, Professor Emeritus, Trinity College; Cartwright, University of Michigan, Research Center for Group Dynamics; Vere Chappell, University of Chicago; John D. Caputo, Professor, Villanova University; Lloyd I. Carr, Husserl Archive; Charles Courtney, Drew University; Geoffrey Clive, Vanderbilt University, Tennessee; Walter Cerf, University of Wisconsin, Madison; Charles A.Corr, Southern Illinois University at Edwardsville, Illinois; Kah Kying Cho, State University of New York, Buffalo. Includes letters from Spiegelberg to: Harry T. Costello, Professor, Trinity College; Charles Courtney, Professor, Drew University; J. Harry Cotton, Professor, Wabash College; Dorwin Cartwright, University of Michigan, Research Center for Group Dynamics; Geoffrey Clive, Vanderbilt University, Tennessee; Walter Cerf, University of Wisconsin, Madison; Charles A. Corr, Southern Illinois University at Edwardsville, Illinois; Kah Kying Cho, State University of New York, Buffalo