[1] Belavin A A, Polyakov A M, Schwarz A S and Tyupkin Y S 1975 Phys. Lett. B 59 85
[2] 't Hooft G 1976 Phys. Rev. D 14 3432
     't Hooft G 1986 Phys. Rep. 142 357
[3] Kaplan D B and Manohar A V 1986 Phys. Rev. Lett. 56 2004
     Choi K 1992 Nucl. Phys. B 383 58
[4] Peccei R D and Quinn H R 1977 Phys. Rev. Lett. 38 1440
     Peccei R D and Quinn H R 1977 Phys. Rev. D 16 1791
[5] Weinberg S 1978 Phys. Rev. Lett. 40 223
     Wilczek F 1978 Phys. Rev. Lett. 40 279
[6] Kim J E 1979 Phys. Rev. Lett. 43 103
     Shifman M A, Vainshtein A I and Zakharov V I 1980 Nucl. Phys. B 166 493
     Dine M, Fishler W and Srednicki M 1981 Phys. Lett. B 104 199
     Zhitnitsky A R 1980 Sov. J. Nucl. Phys. 31 260 [7] Kim J E and Carosi G 2010 Rev. Mod. Phys. 82 557
[8] Weinberg S 1996 The Quantum Theory of Fields (Cambridge: Cambridge University Press) vol 2
[9] Kim J E 1987 Phys. Rep. 150 1
     Turner M S 1990 Phys. Rep. 197 67
     Raffelt G G 1990 Phys. Rep. 198 1
[10] Weinberg S 1995 The Quantum Theory of Fields (Cambridge: Cambridge University Press) vol 1
[11] Bardeen W A and Tye S H H 1978 Phys. Lett. B 74 229
[12] Dicus D A, Kolb E W, Teplitz V L and Wagoner R V 1978 Phys. Rev. D 18 1829