1. Theory of the condensation point
2. For reviews see S. Coleman, Phys. Rev. D 15 (1977) 2929; A. Zichichi (Ed.), also in The Whys of Subnuclear Physics, Erice Lectures 1977, Plenum Press, 1979; I. Afflek, Phys. Rev. Lett. 46 (1981) 391; H. Kleinert, Path Integrals in Quantum Mechanics, Statistics, and Polymer Physics, 2nd ed., World Scientific, Singapore, 1995 (www.physik.fu-berlin.de/ ̃kleinert/b3).
3. Action minima among solutions to a class of Euclidean scalar field equations
4. A.D. Linde, Particle Physicsa and Inflationary Cosmology, Harwood, Chur, Switzerland, 1990.
5. T.W.B. Kibble, J. Phys. A 9 (1976) 1387; Phys. Rep. 67 (1980) 183; for recent discussions see P. McGraw, Phys. Rev. D 57 (1998) 3317, astro-ph/9706182.