1) M. Knudsen : Ann. Phys. 28 (1909) 75; E. H. Kennard : Kinetic theory of gases, McGraw-Hill, 1938; L. B. Loeb : Kinetic theory of gases, McGraw-Hill, 1934.
2) A. Guthrie and R. K. Wakerling : Vacumm equipment and techniques, McGraw-Hill, 1949; A. S. D. Barrett and C. H. Bosanquet : Resistance of ducts to molecular flow, Report BR-296, 1944.