Perhaps you should try some spelling variations:
petriov » petrov (Expand Search), peteriov (Expand Search), petriiov (Expand Search), petruiov (Expand Search)
petruov » petrov (Expand Search), peteruov (Expand Search), petriuov (Expand Search), petruuov (Expand Search)
peterv » peter (Expand Search), peters (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)
petruuo » peteruuo (Expand Search), petriuuo (Expand Search), petruuuo (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 petruov) OR peterv) OR (((petr OR petrui) OR (petruuo OR petruuo)) OR per)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petriov OR petruov) OR peterv) OR (((petr OR petrui) OR (petruuo OR petruuo)) OR per)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop (((petriov OR petruov) OR peterv) OR (((petr OR petrui) OR (petruuo OR petruuo)) OR per)) o.s.*.