Perhaps you should try some spelling variations:
petris » petri (Expand Search), petriis (Expand Search), petrois (Expand Search), peris (Expand Search)
petru » pentru (Expand Search), petri (Expand Search), petriu (Expand Search), petrou (Expand Search), peru (Expand Search)
petrui » pentrui (Expand Search), petrii (Expand Search), petriui (Expand Search), petroui (Expand Search), perui (Expand Search), petri (Expand Search)
petriiv » petriiiv (Expand Search), petroiiv (Expand Search), periiv (Expand Search)
petr » petri (Expand Search), petro (Expand Search), per (Expand Search)
petroi » petrioi (Expand Search), petrooi (Expand Search), peroi (Expand Search), petri (Expand Search), petro (Expand Search), petrov (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 ((petriiv OR periiiv) OR ((petris OR petru) OR (petr OR ((petroi OR petrui) OR peter)))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriiv OR periiiv) OR ((petris OR petru) OR (petr OR ((petroi OR petrui) OR peter)))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriiv OR periiiv) OR ((petris OR petru) OR (petr OR ((petroi OR petrui) OR peter)))) o.s.*.