Perhaps you should try some spelling variations:
petriov » petrov (Expand Search), peteriov (Expand Search), petriiov (Expand Search), petruiov (Expand Search)
petruv » petru (Expand Search), petrov (Expand Search), peteruv (Expand Search), petriuv (Expand Search), petruuv (Expand Search)
petr » peter (Expand Search), petri (Expand Search), petru (Expand Search)
petriouuo » peteriouuo (Expand Search), petriiouuo (Expand Search), petruiouuo (Expand Search)
petroi » peteroi (Expand Search), petrioi (Expand Search), petruoi (Expand Search), petri (Expand Search), petro (Expand Search), petrov (Expand Search)
peteroi » peterdi (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 petruv) OR (((petr OR petriouuo) OR (petroi OR peteroi)) OR per)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriov OR petruv) OR (((petr OR petriouuo) OR (petroi OR peteroi)) OR per)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriov OR petruv) OR (((petr OR petriouuo) OR (petroi OR peteroi)) OR per)) o.s.*.