1. G A Cook, ‘Argon, Helium, and the Rare Gases’ (Vol II Chapter XII on separation and purification) (Interscience 1961).
2. D F Shriver, ‘The Manipulation of Air-Sensitive Compounds’ (Chapter 9, Inert Gas Purification) (McGraw-Hill 1969).
3. G A Cook, ‘Argon, Helium, and the Rare Gases’ Vol I (properties) (Interscience 1961).
4. Mellor’s ‘Comprehensive Treatise on Inorganic and Theoretical Chemistry’ Vol VIII (Supplement 1. Nitrogen) (Longmans 1964).
5. F Din, ‘Thermodynamic Functions of Gases’ (Vol 3, Nitrogen) (Butterworth 1961).