1. Field E, Feller M (1952) Standard Oil of Indiana, USA, US PS 2,691,647. Priority 06.12.1952
2. Hogan JP, Banks RL (1953) Phillips Petroleum, USA, US PS 4,376,851. Priority 27.01.1953
3. Civil Action No. 4319, District Court Delaware, 1980, 494 Federal Suppliment pp 370, 376
4. Fischer M (1943) BASF, Germany, DBP 874 215. Priority 18.12.1943
5. Hall FC, Nash AW (1937) J Inst Pet Technol 23: 679