1. P. A. Redhead, US Patent No. 3743876.
2. W. Steckelmacher and B. Eletcher, J. Vac. Sci. Tech.,9, No. 1, 128 (1972).
3. R. P. Krishnamurthy, Vacuum,22, No. 2, 63 (1972).
4. W. B. Nottingham, Trans. 8th Nat. Vacuum Sympcomb. 2nd Int. Vacuum Congress, Pergamon, Oxford (1961).
5. H. Mainke and G. Reich, in: Sorption Processes in Vacuum [Russian translation], Atomizdat, Moscow (1966), pp. 235?242.