A Dream of Wings, Crouch, T., 1981, pp. 83-84

p.83: "Chanute began to contact those experts in each field who might be willing to prepare [ ] papers. Langley, [ ] Goupil, Maxim, [ ] Wenham, Moy and Hargrave were among those solicited. [ ] The emphasis was to be on describing experiments actually performed. [ ]

p. 84: Langley was one of the few [ ] who was not anxiousto participate, possibly because he was unwillling to make public the results of his ongoing experiments with powered models."