Changes
were shown to be NP-complete, for example the problem introduced here is
<math>NP</math>-complete, if we also fix some other odd-degree nodes where we want
the in-degree to be more than the out-degree. See also </ref>Z. Király, Z. Szigeti, ''Notes on well-balancedorientations'' ]http://www.cs.elte.hu/egres/www/tr-04-10.html EGRES Technical Report no. 2004-10.]</ref> and <ref>A. Bernáth and G. Joret. ''Well-balanced orientations of mixed graphs'' Inf. Process. Lett., 106(4):149-151, 2008. (See the EGRES Quick Proof version QP-2007-01 at www.cs.elte.hu/egres.)</ref>
