Soules is a surname of Southern France, especially of the regions of BORDEAUX and TOULOUSE, up to the Spanish border. I am not sure about its meaning, it could be something that means "full", "satisfied"
See the French site:
www.jtosti.com/noms (surname soulard)
Volkov or Volkoff, comes VOLK a slavic word that means WOLF. A surname like that is spread in European languages.
Yunker or Junker, I think is a surname of german origin it comes from jung.
The Junker were the Germans belonging to the low nobility in 19th century, especially before the German unification (1870).