Perhaps you should try some spelling variations:
perov » petrov (Expand Search)
petruv » peteruv (Expand Search), petruuv (Expand Search), petrouv (Expand Search)
petruuuv » peteruuuv (Expand Search), petruuuuv (Expand Search), petrouuuv (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (Expand Search)
petruui » peteruui (Expand Search), petruuui (Expand Search), petrouui (Expand Search)
petruov » peteruov (Expand Search), petruuov (Expand Search), petrouov (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (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 ((petruv OR petruuuv) OR ((((peteru OR perov) OR (petri OR petruui)) OR petruov) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petruv OR petruuuv) OR ((((peteru OR perov) OR (petri OR petruui)) OR petruov) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petruv OR petruuuv) OR ((((peteru OR perov) OR (petri OR petruui)) OR petruov) OR petr)) o.s.*.