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