Perhaps you should try some spelling variations:
perov » petrov (Expand Search)
petro » petrov (Expand Search), petri (Expand Search), petru (Expand Search), petero (Expand Search), petrio (Expand Search), petruo (Expand Search)
petruuv » peteruuv (Expand Search), petriuuv (Expand Search), petruuuv (Expand Search)
petrui » peterui (Expand Search), petriui (Expand Search), petruui (Expand Search)
petruui » peteruui (Expand Search), petriuui (Expand Search), petruuui (Expand Search)
petr » peter (Expand Search), petri (Expand Search), petru (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 ((petruuv OR perov) OR ((petro OR (((petrui OR petruui) OR peteri) OR petruui)) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petruuv OR perov) OR ((petro OR (((petrui OR petruui) OR peteri) OR petruui)) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petruuv OR perov) OR ((petro OR (((petrui OR petruui) OR peteri) OR petruui)) OR petr)) o.s.*.