Perhaps you should try some spelling variations:
petrov » petro (Expand Search), petruov (Expand Search), petroov (Expand Search), perov (Expand Search)
petriv » petruiv (Expand Search), petroiv (Expand Search), periv (Expand Search)
petris » petruis (Expand Search), petrois (Expand Search), peris (Expand Search)
petriio » petruiio (Expand Search), petroiio (Expand Search), periio (Expand Search)
petroov » petruoov (Expand Search), petrooov (Expand Search), peroov (Expand Search)
petr » petru (Expand Search), petro (Expand Search), per (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 ((petrov OR petriv) OR (((petris OR petriio) OR petroov) OR ((petr OR petri) OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petrov OR petriv) OR (((petris OR petriio) OR petroov) OR ((petr OR petri) OR peter))) o.s.*".