Perhaps you should try some spelling variations:
petruov » petrov (Expand Search), petruuov (Expand Search), petrouov (Expand Search), peruov (Expand Search)
petruv » petru (Expand Search), petrov (Expand Search), petruuv (Expand Search), petrouv (Expand Search), peruv (Expand Search)
petrui » petru (Expand Search), petruui (Expand Search), petroui (Expand Search), perui (Expand Search)
petriov » petrov (Expand Search), petruiov (Expand Search), petroiov (Expand Search), periov (Expand Search)
petr » petru (Expand Search), petro (Expand Search), per (Expand Search)
petroi » petruoi (Expand Search), petrooi (Expand Search), peroi (Expand Search), petro (Expand Search), petrov (Expand Search), petrow (Expand Search)
petri » petrui (Expand Search), petroi (Expand Search), peri (Expand Search)

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: fop ((petruov OR petruv) OR ((petrui OR petriov) OR ((petr OR (petroi OR petri)) OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petruov OR petruv) OR ((petrui OR petriov) OR ((petr OR (petroi OR petri)) OR peter))) o.s.*".