1. F. Spitzer,Principles of Random Walk (Van Nostrand, Princeton, New Jersey, 1964).
2. M. N. Barber and B. W. Ninham,Random and Restricted Walks (Gordon and Breach, New York, 1970).
3. H. Yamakawa,Modern Theory of Polymer Solutions (Harper and Row, New York, 1970); see Chap. 2.
4. E. W. Montroll, inApplied Combinatorial Mathematics, E. F. Beckenback, ed. (Wiley, New York, 1964); and E. W. Montroll,J. Soc. Indust. Appl Math. 4:241 (1956).
5. P. W. Kasteleyn, inGraph Theory and Theoretical Physics, F. Harary, ed. (Academic Press, London, 1967).