[1] Spitzer F 1976 Principles of Random Walk 2nd edn (New
York: Springer)

[2] Barber M N and Ninham B W 1970 Random and Restricted
Walks (New York: Gordon and Breach)

[3] Hughes B D 1996 Random Walks and Random Environments
(Oxford: Clarendon) vols 1 and 2

Erdos P and Renyi A 1959 Publ. Math. 6
290

Erdos P and Renyi A 1960 Publ. Math. Inst. Hung.
Acad. Sci. 5 17

[5] Watts D J and Strogatz S H 1998 Nature 393 440

[6] Barabasi A L and Albert R 1999 Science 286 509

[7] Watts D J 1999 Small Worlds: The Dynamics of Networks
Between Order and Randomness (Princeton, NJ: Princeton University Press)

[8] Dorogovtsev S N and Mendes J F F 2002 Adv. Phys. 51
1079

[9] Newman M E J 2003 SIAM Rev. 45 167

[10] Strogatz S H 2001 Nature 410 268

[11] Pandit S A and Amritkar R E 2001 Phys. Rev. E 63
041104

[12] Lahtinen J, Kertesz J and Kaski K 2001 Phys. Rev. E
64 057105

[13] Almaas E, Kulkarni R V and Stroud D 2003 Phys. Rev. E
68 056105

[14] Parris P E and Kenkre V M 2005 Phys. Rev. E 72
056119

[15] Adamic L A, Lukose R M, Puniyani A R and Huberman B A 2001
Phys. Rev. E 64 046135

[16] Noh J D and Rieger H 2004 Phys. Rev. Lett. 92 118701

Noh J D and Rieger H 2004 Phys. Rev. E 69 036111
(cond-mat/0509564)

[17] Gallos L K 2004 Phys. Rev. E 70 046116

[18] Yang S J 2005 Phys. Rev. E 71 016107

[19] Barrat A, Barthelemy M, Pastor-Satorras R and Vespignai
A 2004 Proc. Natl. Acad. Sci. USA 101 3747

Barrat A, Barthelemy M and Vespignani A 2004 Phys. Rev. Lett.
92 228701

Barrat A, Barthelemy M and Vespignani A 2004 Phys. Rev.
E 70 066149

Barrat A and Pastor-Satorras R 2005 Phys. Rev. E 71 036127

[20] Xu X J, Wu Z X and Wang Y H 2005 Chin. Phys. Lett.
22 1548

[21] Wu Z X, Xu X J and Wang Y H 2005 Phys. Rev. E 71 066124

[22] Yan G, Zhou T, Wang J, Fu Z and Wang B 2005 Chin. Phys. Lett.
22 510

[23] Simonsen I 2005 Physica A 357 317