Perhaps you should try some spelling variations:
petrw » peterw (Expand Search), petrow (Expand Search), perw (Expand Search)
petr » peter (Expand Search), petro (Expand Search), per (Expand Search)
petru » peteru (Expand Search), petrou (Expand Search), peru (Expand Search)
petroov » peteroov (Expand Search), petrooov (Expand Search), peroov (Expand Search)
petrv » peterv (Expand Search), petrov (Expand Search), perv (Expand Search)
petri » peteri (Expand Search), petroi (Expand Search), peri (Expand Search)
perov » petrov (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 (((petrw OR petr) o) OR (((petru OR (((petroov OR perov) OR peruv) OR petrv)) OR petri) _)). s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petrw OR petr) o) OR (((petru OR (((petroov OR perov) OR peruv) OR petrv)) OR petri) _)). s.".
• Adding a wildcard symbol may retrieve word variants: fop (((petrw OR petr) o) OR (((petru OR (((petroov OR perov) OR peruv) OR petrv)) OR petri) _)). s.*.