Perhaps you should try some spelling variations:
petrov » petro (Expand Search), petruov (Expand Search), petroov (Expand Search), perov (Expand Search)
petroov » petruoov (Expand Search), petrooov (Expand Search), peroov (Expand Search)
petr » petru (Expand Search), petro (Expand Search), per (Expand Search)
petri » petrui (Expand Search), petroi (Expand Search), peri (Expand Search)
petris » petruis (Expand Search), petrois (Expand Search), peris (Expand Search)
petrouis » petruouis (Expand Search), petroouis (Expand Search), perouis (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 (((petrov OR petroov) OR ((petr OR petri) OR (petris OR petrouis))) OR peter) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petrov OR petroov) OR ((petr OR petri) OR (petris OR petrouis))) OR peter) o.s.*".