Perhaps you should try some spelling variations:
petriov » peteriov (Expand Search), petriiov (Expand Search), petruiov (Expand Search)
petruuv » peteruuv (Expand Search), petriuuv (Expand Search), petruuuv (Expand Search)
petriiio » peteriiio (Expand Search), petriiiio (Expand Search), petruiiio (Expand Search)
petruo » peteruo (Expand Search), petriuo (Expand Search), petruuo (Expand Search)
petruuo » peteruuo (Expand Search), petriuuo (Expand Search), petruuuo (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 (((petriov OR petriov) OR petruuv) OR ((petriiio OR (petruo OR petruuo)) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petriov OR petriov) OR petruuv) OR ((petriiio OR (petruo OR petruuo)) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop (((petriov OR petriov) OR petruuv) OR ((petriiio OR (petruo OR petruuo)) OR petr)) o.s.*.