Perhaps you should try some spelling variations:
petrov » petro (Expand Search), peterov (Expand Search), petruov (Expand Search), petroov (Expand Search)
petrow » petro (Expand Search), petrowna (Expand Search), peterow (Expand Search), petruow (Expand Search), petroow (Expand Search)
pentruo » pentru (Expand Search)
petriiv » peteriiv (Expand Search), petruiiv (Expand Search), petroiiv (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (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 petriiv) OR ((((petrow OR pentruo) OR petri) OR petrow) OR (petr OR per))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petrov OR petriiv) OR ((((petrow OR pentruo) OR petri) OR petrow) OR (petr OR per))) o.s.*".