1. How nitrogen is produced and used for enhanced recovery;Clancy;World Oil,1981
2. Unique enhanced oil and gas recovery for very high-pressure Wilcox sands uses cryogenic nitrogen and methane mixture;Eckles;J Pet Tech,1981
3. Nitrogen injection takes hold for enhanced recovery;Compressed Air,1982
4. Upgrade low-Btu gas;Jones;Hydrocarbon Processing,1973
5. How to take nitrogen out of a gas stream;Joplin;Petroleum Engineer International,1980