[Energy Focus  Vol. 4, no. 2 (1987); v. 5, no. 1 (1988); v. 12, no. 3 (1995); v.13, no. 3 (1996); v. 18, no. 1 (2001);v. 19, no. 1 (2002)-v. 24, no. 3 (2007); ]