Perhaps you should try some spelling variations:
perov » petrov (Expand Search)
peru » per (Expand Search)
petru » peteru (Expand Search), petriu (Expand Search), petrou (Expand Search)
petroi » peteroi (Expand Search), petrioi (Expand Search), petrooi (Expand Search)
petroiuo » peteroiuo (Expand Search), petrioiuo (Expand Search), petrooiuo (Expand Search)
petriiuo » peteriiuo (Expand Search), petriiiuo (Expand Search), petroiiuo (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 peterov) OR ((((petru OR petroi) OR peru) OR (petroiuo OR petriiuo)) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((perov OR peterov) OR ((((petru OR petroi) OR peru) OR (petroiuo OR petriiuo)) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((perov OR peterov) OR ((((petru OR petroi) OR peru) OR (petroiuo OR petriiuo)) OR petr)) o.s.*.