Perhaps you should try some spelling variations:
petroov » petrov (Expand Search), peteroov (Expand Search), petruoov (Expand Search), petrooov (Expand Search)
peterov » petrov (Expand Search)
petruv » petru (Expand Search), petrov (Expand Search), peteruv (Expand Search), petruuv (Expand Search), petrouv (Expand Search)
petrou » petru (Expand Search), petro (Expand Search), petrov (Expand Search), peterou (Expand Search), petruou (Expand Search), petroou (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (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 peterov) OR petruv) OR peruov) OR (petrou OR ((petr OR per) OR petri))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petroov OR peterov) OR petruv) OR peruov) OR (petrou OR ((petr OR per) OR petri))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((((petroov OR peterov) OR petruv) OR peruov) OR (petrou OR ((petr OR per) OR petri))) o.s.*.