Perhaps you should try some spelling variations:
perov » petrov (Expand Search)
petruv » peteruv (Expand Search), petrouv (Expand Search), peruv (Expand Search)
petrv » peterv (Expand Search), petrov (Expand Search), perv (Expand Search)
petri » peteri (Expand Search), petroi (Expand Search), peri (Expand Search)
petru » peteru (Expand Search), petrou (Expand Search), peru (Expand Search)
petroio » peteroio (Expand Search), petrooio (Expand Search), peroio (Expand Search)
petr » peter (Expand Search), petro (Expand Search), per (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 (((perov OR petruv) OR petrv) OR (((petri OR petru) OR (perio OR petroio)) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((perov OR petruv) OR petrv) OR (((petri OR petru) OR (perio OR petroio)) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop (((perov OR petruv) OR petrv) OR (((petri OR petru) OR (perio OR petroio)) OR petr)) o.s.*.