Clay Pipe Institute.
Harold E. Babbitt
D. R. Atkinson
Edward Penner
Lonnie Lee Abernethy
National Clay Pipe Institute (U.S.)
Allan Peacey
Rex L. Wilson
Friedrich G. Schulze
Edward Fletcher
Lloyd Edwards
Eastern Clay Products Association
Leon Lefêvre
Iain C. Walker
André Leclaire
Colin Spencer Southall
S. D. White
Peter Davey