Perhaps you should try some spelling variations:
perov » petrov (Expand Search)
petroov » peteroov (Expand Search), petrioov (Expand Search), petrooov (Expand Search)
petru » peteru (Expand Search), petriu (Expand Search), petrou (Expand Search)
petroi » peteroi (Expand Search), petrioi (Expand Search), petrooi (Expand Search)
petroui » peteroui (Expand Search), petrioui (Expand Search), petrooui (Expand Search)
petruo » peteruo (Expand Search), petriuo (Expand Search), petrouo (Expand Search)
petr » peter (Expand Search), petri (Expand Search), petro (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 ((perov OR petroov) OR ((((pero OR petru) OR (petroi OR petroui)) OR petruo) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((perov OR petroov) OR ((((pero OR petru) OR (petroi OR petroui)) OR petruo) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((perov OR petroov) OR ((((pero OR petru) OR (petroi OR petroui)) OR petruo) OR petr)) o.s.*.