Erratum for the paper 
Game-Tree Search Using Proof Numbers: The First Twenty Years.
ICGA Journal 35(3), 131-156, 2012.

page 137, Figure 3, lines 49-51:
The initialization of int value should be moved inside the while loop:
node best;
while (N.expanded) {
    int value = \infty;
    ...

Thanks to Yeqin Zhang for pointing out this error.