Perhaps you should try some spelling variations:
perov » petrov (Expand Search)
petro » petrov (Expand Search), petri (Expand Search), petero (Expand Search), petrio (Expand Search), pero (Expand Search)
petriiv » peteriiv (Expand Search), petriiiv (Expand Search), periiv (Expand Search)
petruv » peteruv (Expand Search), petriuv (Expand Search), peruv (Expand Search)
petru » peteru (Expand Search), petriu (Expand Search), peru (Expand Search)
petruo » peteruo (Expand Search), petriuo (Expand Search), peruo (Expand Search)
petr » peter (Expand Search), petri (Expand Search), per (Expand Search)

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: fop (((petriiv OR perov) OR petruv) OR (((petro OR petru) OR petruo) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petriiv OR perov) OR petruv) OR (((petro OR petru) OR petruo) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop (((petriiv OR perov) OR petruv) OR (((petro OR petru) OR petruo) OR petr)) o.s.*.