Perhaps you should try some spelling variations:
petroov » petrov (Expand Search), petruoov (Expand Search), petrooov (Expand Search), peroov (Expand Search)
petruov » petrov (Expand Search), petruuov (Expand Search), petrouov (Expand Search), peruov (Expand Search)
petriov » petrov (Expand Search), petruiov (Expand Search), petroiov (Expand Search), periov (Expand Search)
petroiv » petrov (Expand Search), petruoiv (Expand Search), petrooiv (Expand Search), peroiv (Expand Search)
petr » petru (Expand Search), petro (Expand Search), per (Expand Search)
petri » petrui (Expand Search), petroi (Expand Search), peri (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 petruov) OR petriov) OR petroiv) OR (periuo OR ((petr OR petri) OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petroov OR petruov) OR petriov) OR petroiv) OR (periuo OR ((petr OR petri) OR peter))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((((petroov OR petruov) OR petriov) OR petroiv) OR (periuo OR ((petr OR petri) OR peter))) o.s.*.