Perhaps you should try some spelling variations:
petris » petri (Expand Search), petriis (Expand Search), petrois (Expand Search), peris (Expand Search)
petriiv » petriiiv (Expand Search), petroiiv (Expand Search), periiv (Expand Search)
petrois » petriois (Expand Search), petroois (Expand Search), perois (Expand Search)
petruuo » petriuuo (Expand Search), petrouuo (Expand Search), peruuo (Expand Search), pentruuo (Expand Search), petriuo (Expand Search)
petriuo » petriiuo (Expand Search), petroiuo (Expand Search), periuo (Expand Search)
petr » petri (Expand Search), petro (Expand Search), per (Expand Search)
petru » petriu (Expand Search), petrou (Expand Search), peru (Expand Search), pentru (Expand Search), petri (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 (petris OR petrois)) OR ((petruuo OR petriuo) OR ((petr OR petru) OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriiv OR (petris OR petrois)) OR ((petruuo OR petriuo) OR ((petr OR petru) OR peter))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriiv OR (petris OR petrois)) OR ((petruuo OR petriuo) OR ((petr OR petru) OR peter))) o.s.*.