Perhaps you should try some spelling variations:
petrov » petro (Expand Search), petruov (Expand Search), petroov (Expand Search), perov (Expand Search)
petrio » petris (Expand Search), petro (Expand Search), petruio (Expand Search), petroio (Expand Search), perio (Expand Search)
petero » petro (Expand Search)
peters » petersen (Expand Search)
petri » petrui (Expand Search), petroi (Expand Search), peri (Expand Search)
petr » petru (Expand Search), petro (Expand Search), per (Expand Search)
petroui » petruoui (Expand Search), petrooui (Expand Search), peroui (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 petri) OR ((petrio OR (petero OR peters)) OR ((petr OR petroui) OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petrov OR petri) OR ((petrio OR (petero OR peters)) OR ((petr OR petroui) OR peter))) o.s.*".