Perhaps you should try some spelling variations:
perov » petrov (Expand Search)
peri » petri (Expand Search), per (Expand Search)
petruv » peteruv (Expand Search), petriuv (Expand Search), petruuv (Expand Search)
petriu » peteriu (Expand Search), petriiu (Expand Search), petruiu (Expand Search)
petruuo » peteruuo (Expand Search), petriuuo (Expand Search), petruuuo (Expand Search)
petruuuo » peteruuuo (Expand Search), petriuuuo (Expand Search), petruuuuo (Expand Search)
petr » peter (Expand Search), petri (Expand Search), petru (Expand Search)

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 ((((petriu OR pero) OR peri) OR (petruuo OR petruuuo)) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((perov OR petruv) OR ((((petriu OR pero) OR peri) OR (petruuo OR petruuuo)) OR petr)) o.s.*".