Perhaps you should try some spelling variations:
petrois » petris (Expand Search), petruois (Expand Search), petroois (Expand Search), perois (Expand Search)
petruov » petrov (Expand Search), petruuov (Expand Search), petrouov (Expand Search), peruov (Expand Search)
petruuv » petruuuv (Expand Search), petrouuv (Expand Search), peruuv (Expand Search)
petr » petru (Expand Search), petro (Expand Search), per (Expand Search)
petri » petrui (Expand Search), petroi (Expand Search), peri (Expand Search)
petero » peters (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 (((petrois OR petruuv) OR petruov) OR ((((petr OR petri) OR petero) OR petero) OR peter)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petrois OR petruuv) OR petruov) OR ((((petr OR petri) OR petero) OR petero) OR peter)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop (((petrois OR petruuv) OR petruov) OR ((((petr OR petri) OR petero) OR petero) OR peter)) o.s.*.