Perhaps you should try some spelling variations:
perov » petrov (Expand Search)
petro » petrov (Expand Search), petru (Expand Search), petero (Expand Search), petruo (Expand Search), pero (Expand Search)
peri » per (Expand Search)
petruo » peteruo (Expand Search), petruuo (Expand Search), peruo (Expand Search)
petruuo » peteruuo (Expand Search), petruuuo (Expand Search), peruuo (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), peri (Expand Search)
petr » peter (Expand Search), petru (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 ((((petro OR pero) OR (petruo OR petruuo)) OR (petri OR peri)) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (perov OR ((((petro OR pero) OR (petruo OR petruuo)) OR (petri OR peri)) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop (perov OR ((((petro OR pero) OR (petruo OR petruuo)) OR (petri OR peri)) OR petr)) o.s.*.