Perhaps you should try some spelling variations:
petrov » petro (Expand Search), petriov (Expand Search), petroov (Expand Search), perov (Expand Search)
petroi » petri (Expand Search), petro (Expand Search), petrow (Expand Search), petrioi (Expand Search), petrooi (Expand Search), peroi (Expand Search)
petroov » petrioov (Expand Search), petrooov (Expand Search), peroov (Expand Search)
petrioov » petriioov (Expand Search), petroioov (Expand Search), perioov (Expand Search)
petr » petri (Expand Search), petro (Expand Search), per (Expand Search)
petru » petriu (Expand Search), petrou (Expand Search), peru (Expand Search), pentru (Expand Search), petri (Expand Search)
petris » petriis (Expand Search), petrois (Expand Search), peris (Expand Search), petri (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 petroi) OR (petroov OR petrioov)) OR ((petr OR petru) OR petris)) OR peter) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petrov OR petroi) OR (petroov OR petrioov)) OR ((petr OR petru) OR petris)) OR peter) o.s.*".