Perhaps you should try some spelling variations:
peri » petri (Expand Search), per (Expand Search)
petriov » peteriov (Expand Search), petriiov (Expand Search), petroiov (Expand Search)
petruv » peteruv (Expand Search), petriuv (Expand Search), petrouv (Expand Search)
petriuv » peteriuv (Expand Search), petriiuv (Expand Search), petroiuv (Expand Search)
petrouv » peterouv (Expand Search), petriouv (Expand Search), petroouv (Expand Search)
petru » peteru (Expand Search), petriu (Expand Search), petrou (Expand Search)
petr » peter (Expand Search), petri (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 ((petriov OR ((petruv OR petriuv) OR petrouv)) OR ((petru OR peri) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriov OR ((petruv OR petriuv) OR petrouv)) OR ((petru OR peri) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriov OR ((petruv OR petriuv) OR petrouv)) OR ((petru OR peri) OR petr)) o.s.*.