Perhaps you should try some spelling variations:
petriow » petrow (Expand Search), petriiow (Expand Search), petruiow (Expand Search), petroiow (Expand Search)
petr » petri (Expand Search), petru (Expand Search), petro (Expand Search)
petriov » petriiov (Expand Search), petruiov (Expand Search), petroiov (Expand Search), petrov (Expand Search)
petrui » petriui (Expand Search), petruui (Expand Search), petroui (Expand Search), petri (Expand Search), petru (Expand Search)
petruui » petriuui (Expand Search), petruuui (Expand Search), petrouui (Expand Search)
petruuuui » petriuuuui (Expand Search), petruuuuui (Expand Search), petrouuuui (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 (((petriow OR (petr OR peter)) o) OR ((petriov OR ((petrui OR petruui) OR petruuuui)) _)). s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petriow OR (petr OR peter)) o) OR ((petriov OR ((petrui OR petruui) OR petruuuui)) _)). s.".
• Adding a wildcard symbol may retrieve word variants: fop (((petriow OR (petr OR peter)) o) OR ((petriov OR ((petrui OR petruui) OR petruuuui)) _)). s.*.