Perhaps you should try some spelling variations:
petrov » petro (Expand Search), petruov (Expand Search), petroov (Expand Search), perov (Expand Search)
petroi » petro (Expand Search), petrow (Expand Search), petruoi (Expand Search), petrooi (Expand Search), peroi (Expand Search)
petriov » petruiov (Expand Search), petroiov (Expand Search), periov (Expand Search)
petris » petruis (Expand Search), petrois (Expand Search), peris (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 (((petriov OR petrov) OR ((petroi OR periia) OR petris)) OR ((petr OR petri) OR peter)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petriov OR petrov) OR ((petroi OR periia) OR petris)) OR ((petr OR petri) OR peter)) o.s.*".