8Chen T J,Ruzish P A.Multiple feed process for the production of propylene:US,6339181[P].2002-01-15.
9Donker C P,Lenselink B,Theelen M H,et al.Aliphatic petroleumbased resins having controlled softening points and molecular weights and hot melt pressure sensitive adhesive containing same:US,6106939[P].2000-08-22.
10Small A B,Hughes V L,Benitez F M,et al.Process for preparing light colored petroleum resins and resins produced thereby (CS-203):US,4391961[P].1983-07-05.