Perhaps you should try some spelling variations:
petris » petri (Expand Search), peteris (Expand Search), petriis (Expand Search), petruis (Expand Search)
peters » peter (Expand Search), petersen (Expand Search)
petruo » petru (Expand Search), petro (Expand Search), peteruo (Expand Search), petriuo (Expand Search), petruuo (Expand Search)
peteri » peterdi (Expand Search), peter (Expand Search), petri (Expand Search)
petriio » peteriio (Expand Search), petriiio (Expand Search), petruiio (Expand Search)
petr » peter (Expand Search), petri (Expand Search), petru (Expand Search)
petrui » peterui (Expand Search), petriui (Expand Search), petruui (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 peters) OR (((petruo OR peteri) OR petriio) OR (petr OR (petrui OR peteri)))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petris OR peters) OR (((petruo OR peteri) OR petriio) OR (petr OR (petrui OR peteri)))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petris OR peters) OR (((petruo OR peteri) OR petriio) OR (petr OR (petrui OR peteri)))) o.s.*.