Perhaps you should try some spelling variations:
perov » petrov (Expand Search)
petriv » peteriv (Expand Search), petroiv (Expand Search), periv (Expand Search)
petri » peteri (Expand Search), petroi (Expand Search), peri (Expand Search)
petru » peteru (Expand Search), petrou (Expand Search), peru (Expand Search)
petrio » peterio (Expand Search), petroio (Expand Search), perio (Expand Search)
petriuo » peteriuo (Expand Search), petroiuo (Expand Search), periuo (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 petriv) OR ((((petri OR petru) OR (petrio OR peterio)) OR petriuo) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((perov OR petriv) OR ((((petri OR petru) OR (petrio OR peterio)) OR petriuo) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((perov OR petriv) OR ((((petri OR petru) OR (petrio OR peterio)) OR petriuo) OR petr)) o.s.*.