Perhaps you should try some spelling variations:
petriov » petrov (Expand Search), petriiov (Expand Search), petruiov (Expand Search), petroiov (Expand Search)
petero » peters (Expand Search), petro (Expand Search)
petrooi » petriooi (Expand Search), petruooi (Expand Search), petroooi (Expand Search)
petr » petri (Expand Search), petru (Expand Search), petro (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)

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 (petriov OR ((petrooi OR petero) OR ((petr OR (petrui OR petruui)) OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (petriov OR ((petrooi OR petero) OR ((petr OR (petrui OR petruui)) OR peter))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop (petriov OR ((petrooi OR petero) OR ((petr OR (petrui OR petruui)) OR peter))) o.s.*.