 | 05-04-2016 Piet Bouma: |
R, see book of Ben en Yushkevitch , 700 selected problems of Ukrainian championship p 24 #305 N. Boreiko. Too it is known the authors variation of this problem which was published in the former USSR press in 1981 6,10,13,19,20,25,30,36,40-16,21,29,32,33,37,38,41,42,49. Sol. 11,31,33,4, 43 etc.the exact date of publication may be asked from the author, if is necessary.