Perhaps you should try some spelling variations:
perov » petrov (Expand Search)
peru » per (Expand Search)
perui » peri (Expand Search)
petruv » peteruv (Expand Search), petrouv (Expand Search), peruv (Expand Search)
petru » peteru (Expand Search), petrou (Expand Search), peru (Expand Search)
petri » peteri (Expand Search), petroi (Expand Search), peri (Expand Search)
petrouui » peterouui (Expand Search), petroouui (Expand Search), perouui (Expand Search)
petr » peter (Expand Search), petro (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 ((petruv OR perov) OR (((petru OR peru) OR ((petri OR perui) OR petrouui)) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petruv OR perov) OR (((petru OR peru) OR ((petri OR perui) OR petrouui)) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petruv OR perov) OR (((petru OR peru) OR ((petri OR perui) OR petrouui)) OR petr)) o.s.*.