Perhaps you should try some spelling variations:
petris » petri (Expand Search), peteris (Expand Search), petriis (Expand Search), petruis (Expand Search)
petruo » petru (Expand Search), petro (Expand Search), peteruo (Expand Search), petriuo (Expand Search), petruuo (Expand Search)
petruiv » peteruiv (Expand Search), petriuiv (Expand Search), petruuiv (Expand Search)
petruio » peteruio (Expand Search), petriuio (Expand Search), petruuio (Expand Search)
petrioio » peterioio (Expand Search), petriioio (Expand Search), petruioio (Expand Search)
petr » peter (Expand Search), petri (Expand Search), petru (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 ((petris OR petruiv) OR (((petruio OR petrioio) OR petruo) OR (petr OR peterdi))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petris OR petruiv) OR (((petruio OR petrioio) OR petruo) OR (petr OR peterdi))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petris OR petruiv) OR (((petruio OR petrioio) OR petruo) OR (petr OR peterdi))) o.s.*.