Perhaps you should try some spelling variations:
perov » petrov (Expand Search)
peru » petru (Expand Search), per (Expand Search)
petruv » peteruv (Expand Search), petruuv (Expand Search), petrouv (Expand Search)
petrou » peterou (Expand Search), petruou (Expand Search), petroou (Expand Search)
petroou » peteroou (Expand Search), petruoou (Expand Search), petrooou (Expand Search)
petriu » peteriu (Expand Search), petruiu (Expand Search), petroiu (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (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 ((perov OR petruv) OR ((((petrou OR petroou) OR peru) OR petriu) OR (petri OR petr))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((perov OR petruv) OR ((((petrou OR petroou) OR peru) OR petriu) OR (petri OR petr))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((perov OR petruv) OR ((((petrou OR petroou) OR peru) OR petriu) OR (petri OR petr))) o.s.*.