Perhaps you should try some spelling variations:
petriov » peteriov (Expand Search), petriiov (Expand Search), petruiov (Expand Search)
petruov » peteruov (Expand Search), petriuov (Expand Search), petruuov (Expand Search)
petruuv » peteruuv (Expand Search), petriuuv (Expand Search), petruuuv (Expand Search)
petrui » peterui (Expand Search), petriui (Expand Search), petruui (Expand Search)
petruo » peteruo (Expand Search), petriuo (Expand Search), petruuo (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 petruov) OR petruuv) OR ((((petrui OR petruo) OR per) OR petruo) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petriov OR petruov) OR petruuv) OR ((((petrui OR petruo) OR per) OR petruo) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop (((petriov OR petruov) OR petruuv) OR ((((petrui OR petruo) OR per) OR petruo) OR petr)) o.s.*.