Perhaps you should try some spelling variations:
perov » petrov (Expand Search)
petro » petrov (Expand Search), petri (Expand Search), petru (Expand Search), petero (Expand Search), petrio (Expand Search), petruo (Expand Search)
petriov » peteriov (Expand Search), petriiov (Expand Search), petruiov (Expand Search)
petruv » peteruv (Expand Search), petriuv (Expand Search), petruuv (Expand Search)
petruuv » peteruuv (Expand Search), petriuuv (Expand Search), petruuuv (Expand Search)
petr » peter (Expand Search), petri (Expand Search), petru (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 ((((petriov OR perov) OR (petruv OR petruuv)) OR peterv) OR ((petro OR peteri) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petriov OR perov) OR (petruv OR petruuv)) OR peterv) OR ((petro OR peteri) OR petr)) o.s.*".