Perhaps you should try some spelling variations:
petriov » peteriov (Expand Search), petriiov (Expand Search), petroiov (Expand Search)
petruov » peteruov (Expand Search), petriuov (Expand Search), petrouov (Expand Search)
petruv » peteruv (Expand Search), petriuv (Expand Search), petrouv (Expand Search)
petriu » peteriu (Expand Search), petriiu (Expand Search), petroiu (Expand Search)
petru » peteru (Expand Search), petriu (Expand Search), petrou (Expand Search)
petrio » peterio (Expand Search), petriio (Expand Search), petroio (Expand Search)
petr » peter (Expand Search), petri (Expand Search), petro (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 petruv) OR petriov) OR (petriu OR ((petru OR petrio) OR petr))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petriov OR petruov) OR petruv) OR petriov) OR (petriu OR ((petru OR petrio) OR petr))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((((petriov OR petruov) OR petruv) OR petriov) OR (petriu OR ((petru OR petrio) OR petr))) o.s.*.