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