Train your brain
Grätzer, George A..
Train your brain: a year's worth of puzzles /
George Grätzer ; translated by Tom Artin
. - Boca Raton : A.K. Peters/CRC Press, 2011
. - xviii, 235 p. ill. 23 cm.
978-1-56881-710-1
978-1-56881-710-1