Perhaps you should try some spelling variations:
petriov » petrov (Expand Search), peteriov (Expand Search), petruiov (Expand Search), petroiov (Expand Search)
petruov » petrov (Expand Search), peteruov (Expand Search), petruuov (Expand Search), petrouov (Expand Search)
petrv » petrov (Expand Search), petru (Expand Search), petro (Expand Search), peterv (Expand Search), petruv (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (Expand Search)
petriv » peteriv (Expand Search), petruiv (Expand Search), petroiv (Expand Search), petrov (Expand Search)
petris » peteris (Expand Search), petruis (Expand Search), petrois (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (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 ((petrv OR petr) OR peteriuv)) OR (petriv OR petris)) OR petri) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petriov OR petruov) OR ((petrv OR petr) OR peteriuv)) OR (petriv OR petris)) OR petri) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((((petriov OR petruov) OR ((petrv OR petr) OR peteriuv)) OR (petriv OR petris)) OR petri) o.s.*.