Perhaps you should try some spelling variations:
petrio » petri (Expand Search), petris (Expand Search), petro (Expand Search), petriio (Expand Search), petroio (Expand Search), perio (Expand Search)
petero » petro (Expand Search)
peters » petersen (Expand Search)
petr » petri (Expand Search), petro (Expand Search), per (Expand Search)
petrii » petriii (Expand Search), petroii (Expand Search), perii (Expand Search), petri (Expand Search), petris (Expand Search)
petru » petriu (Expand Search), petrou (Expand Search), peru (Expand Search), pentru (Expand Search), petri (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 (periv OR ((petrio OR (petero OR peters)) OR ((petr OR (petrii OR petru)) OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (periv OR ((petrio OR (petero OR peters)) OR ((petr OR (petrii OR petru)) OR peter))) o.s.*".