Perhaps you should try some spelling variations:
petriov » peteriov (Expand Search), petroiov (Expand Search), periov (Expand Search)
petruv » peteruv (Expand Search), petrouv (Expand Search), peruv (Expand Search)
petri » peteri (Expand Search), petroi (Expand Search), peri (Expand Search)
petrio » peterio (Expand Search), petroio (Expand Search), perio (Expand Search)
petru » peteru (Expand Search), petrou (Expand Search), peru (Expand Search)
petruo » peteruo (Expand Search), petrouo (Expand Search), peruo (Expand Search)
petr » peter (Expand Search), petro (Expand Search), per (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 ((petriov OR petruv) OR ((((petri OR petrio) OR petru) OR petruo) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriov OR petruv) OR ((((petri OR petrio) OR petru) OR petruo) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriov OR petruv) OR ((((petri OR petrio) OR petru) OR petruo) OR petr)) o.s.*.