Perhaps you should try some spelling variations:
petrov » petruv (Expand Search), peterov (Expand Search), petruov (Expand Search), perov (Expand Search)
petroi » petrui (Expand Search), peteroi (Expand Search), petruoi (Expand Search), peroi (Expand Search)
petro » petru (Expand Search), petero (Expand Search), petruo (Expand Search), pero (Expand Search)
petriv » peteriv (Expand Search), petruiv (Expand Search), periv (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), peri (Expand Search)
petr » peter (Expand Search), petru (Expand Search), per (Expand Search)

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: fop ((petriv OR petrov) OR (((pero OR (petri OR petroi)) OR petero) OR (petro OR petr))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriv OR petrov) OR (((pero OR (petri OR petroi)) OR petero) OR (petro OR petr))) o.s.*".