ΠΟΥ ΕΙΝΑΙ Η ΠΡΑΣΙΝΗ ΠΛΕΥΡΑ ; ΜΠΡΟΣΤΑ Η ΠΙΣΩ;
Where
is the green side ? On the front of the cube or at the back ? Keep
looking at the cube and you'll find that it switches a few times. First
described by professor L. Necker who noticed this while studying
drawings of crystals. |