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)
petriuv » peteriuv (Expand Search), petriiuv (Expand Search), petruiuv (Expand Search)
petriiouv » peteriiouv (Expand Search), petriiiouv (Expand Search), petruiiouv (Expand Search)
petruuou » peteruuou (Expand Search), petriuuou (Expand Search), petruuuou (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 peterov) OR (petriuv OR petriiouv)) OR (petruuou OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petriov OR petruov) OR peterov) OR (petriuv OR petriiouv)) OR (petruuou OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((((petriov OR petruov) OR peterov) OR (petriuv OR petriiouv)) OR (petruuou OR petr)) o.s.*.