Der neue SASS: Plattdeutsches Wörterbuch, Plattdeutsch - Hochdeutsch, Hochdeutsch - Plattdeutsch. Plattdeutsche Rechtschreibung, sixth revised edition (2011, ISBN 978-3-529-03000-0, Wachholtz Verlag, Neumünster)
Etymology
From Middle Low Germanvan dage, compare Dutch vandaag. The word vun/von is replacing native van in some regions in later times, possibly due to High German influence, but is native to some Low German dialects, notably in Eastphalia.