Perhaps you should try some spelling variations:
petrw » petrow (Expand Search), petru (Expand Search), petro (Expand Search), peterw (Expand Search), petruw (Expand Search)
petriov » petrov (Expand Search), peteriov (Expand Search), petruiov (Expand Search), petroiov (Expand Search)
peterow » petrow (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (Expand Search)
petrui » peterui (Expand Search), petruui (Expand Search), petroui (Expand Search), petru (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 petriov) OR peterow) OR peterow) o) OR (((petr OR petri) OR petrui) _)). s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((((petrw OR petriov) OR peterow) OR peterow) o) OR (((petr OR petri) OR petrui) _)). s.".
• Adding a wildcard symbol may retrieve word variants: fop (((((petrw OR petriov) OR peterow) OR peterow) o) OR (((petr OR petri) OR petrui) _)). s.*.