Perhaps you should try some spelling variations:
perov » petrov (Expand Search)
petruov » peteruov (Expand Search), petriuov (Expand Search), petruuov (Expand Search)
petroou » peteroou (Expand Search), petrioou (Expand Search), petruoou (Expand Search)
petroi » peteroi (Expand Search), petrioi (Expand Search), petruoi (Expand Search)
petroui » peteroui (Expand Search), petrioui (Expand Search), petruoui (Expand Search)
petriui » peteriui (Expand Search), petriiui (Expand Search), petruiui (Expand Search)
petr » peter (Expand Search), petri (Expand Search), petru (Expand Search)

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: fop ((petruov OR perov) OR ((((petroou OR pero) OR petroi) OR (petroui OR petriui)) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petruov OR perov) OR ((((petroou OR pero) OR petroi) OR (petroui OR petriui)) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petruov OR perov) OR ((((petroou OR pero) OR petroi) OR (petroui OR petriui)) OR petr)) o.s.*.