Perhaps you should try some spelling variations:
petri » petroi (Expand Search), peri (Expand Search)
petr » petro (Expand Search), per (Expand Search)
petrou » petroou (Expand Search), perou (Expand Search), petro (Expand Search), petrov (Expand Search)
petru » petrou (Expand Search), peru (Expand Search), pentru (Expand Search)
petroi » petrooi (Expand Search), peroi (Expand Search), petro (Expand Search), petrov (Expand Search)
petrow » petroow (Expand Search), perow (Expand Search), petro (Expand Search), petrov (Expand Search), petrowna (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 (((petri OR petr) OR peruov) OR (((petrou OR petru) OR (petroi OR petrow)) OR peter)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petri OR petr) OR peruov) OR (((petrou OR petru) OR (petroi OR petrow)) OR peter)) o.s.*".