Perhaps you should try some spelling variations:
petroov » petrov (Expand Search), peteroov (Expand Search), petrioov (Expand Search), petrooov (Expand Search)
petruv » petrov (Expand Search), peteruv (Expand Search), petriuv (Expand Search), petrouv (Expand Search), pentruv (Expand Search), petriv (Expand Search)
petr » peter (Expand Search), petri (Expand Search), petro (Expand Search)
petru » peteru (Expand Search), petriu (Expand Search), petrou (Expand Search), pentru (Expand Search), petri (Expand Search)
petroi » peteroi (Expand Search), petrioi (Expand Search), petrooi (Expand Search), petri (Expand Search), petro (Expand Search), petrov (Expand Search)
peterow » petrow (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 ((petroov OR petruv) OR (((petr OR (petru OR petersen)) OR (petroi OR peterow)) OR per)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petroov OR petruv) OR (((petr OR (petru OR petersen)) OR (petroi OR peterow)) OR per)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petroov OR petruv) OR (((petr OR (petru OR petersen)) OR (petroi OR peterow)) OR per)) o.s.*.