Book reviews : Semigroups and automata. SelectaUno Kaljulaid (1941-1999). Edited by Jaak Peetre (Lund, Sweden) and Jaan Penjam (Tallinn, Estonia), 2006, IOS Press, Amsterdam. ISBN 1-58603-582-7Lumiste, ÜloProceedings of the Estonian Academy of Sciences. Physics. Mathematics2006 / p. 189-191