Answer:
US, Japan, UK, France, Yugoslavia, Belgium, Italy, Romania, Australia, Greece, Germany, Portugal, Siam, Canada, India, Poland, South Africa, New Zealand, Bolivia, Brazil, China, Cuba, Ecuador, Guatemala, Haiti, Kingdom of Hedjaz, Honduras, Liberia, Nicaragua, Panama, Peru, Romania, Czechoslovakia, Uruguay.
Explanation: 32 countries with 66 representatives. The countries were split into 3 major parties.