Perhaps you should try some spelling variations:
petrooov » petrov (Expand Search), peterooov (Expand Search), petriooov (Expand Search), petruooov (Expand Search)
petriiv » peteriiv (Expand Search), petriiiv (Expand Search), petruiiv (Expand Search)
petroi » peteroi (Expand Search), petrioi (Expand Search), petruoi (Expand Search)
petrui » peterui (Expand Search), petriui (Expand Search), petruui (Expand Search)
petroov » peteroov (Expand Search), petrioov (Expand Search), petruoov (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 ((petriiv OR petriiv) OR (((petroi OR petrui) OR (petroov OR petrooov)) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriiv OR petriiv) OR (((petroi OR petrui) OR (petroov OR petrooov)) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriiv OR petriiv) OR (((petroi OR petrui) OR (petroov OR petrooov)) OR petr)) o.s.*.