Perhaps you should try some spelling variations:
petruov » petrov (Expand Search), petriuov (Expand Search), petruuov (Expand Search), petrouov (Expand Search)
petroi » petri (Expand Search), petro (Expand Search), petrov (Expand Search), petrioi (Expand Search), petruoi (Expand Search), petrooi (Expand Search)
petrou » petru (Expand Search), petro (Expand Search), petrov (Expand Search), petriou (Expand Search), petruou (Expand Search), petroou (Expand Search)
petrio » petri (Expand Search), petris (Expand Search), petro (Expand Search), petriio (Expand Search), petruio (Expand Search), petroio (Expand Search)
petr » petri (Expand Search), petru (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 ((((petruov OR petroi) OR periv) OR petroi) OR ((petrou OR petrio) OR (petr OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petruov OR petroi) OR periv) OR petroi) OR ((petrou OR petrio) OR (petr OR peter))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((((petruov OR petroi) OR periv) OR petroi) OR ((petrou OR petrio) OR (petr OR peter))) o.s.*.