1. Aldous, D.: www.stat.berkeley.edu/~aldous/research/op/sgap.html
2. Cambridge Mathematical Library;N. Biggs,1993
3. Caputo, P., Liggett, T.M., Richthammer, T.: A recursive proof of Aldous’ spectral gap conjecture. arXiv:0906.1238v3 (2009)
4. CBMS Regional Conference Series in Mathematics;F.R.K. Chung,1997
5. Pure and Applied Mathematics;C.W. Curtis,1962