Voltage implies potential difference & for a difference to exist there must be two different points.Node voltage does not make any sense to me as it represent voltage at a point.So what does it actually mean.
Why not try Google or something similar - the web should be your best resource in this matter. Start with the search term "Node Voltage" and see where that leads you.
The work you do yourself tends to be the most rewarding rather than relying on others to do it for you.