Perhaps you should try some spelling variations:
petrov » peterov (Expand Search), petriov (Expand Search), petruov (Expand Search)
petriv » peteriv (Expand Search), petriiv (Expand Search), petruiv (Expand Search)
petruo » peteruo (Expand Search), petriuo (Expand Search), petruuo (Expand Search)
petruuo » peteruuo (Expand Search), petriuuo (Expand Search), petruuuo (Expand Search)
petriiio » peteriiio (Expand Search), petriiiio (Expand Search), petruiiio (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 (((petrov OR peterov) OR petriv) OR (((petruo OR petruuo) OR petriiio) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petrov OR peterov) OR petriv) OR (((petruo OR petruuo) OR petriiio) OR petr)) o.s.*".