Perhaps you should try some spelling variations:
perov » petrov (Expand Search)
peri » petri (Expand Search), per (Expand Search)
petriov » peteriov (Expand Search), petriiov (Expand Search), petroiov (Expand Search)
petrioiov » peterioiov (Expand Search), petriioiov (Expand Search), petroioiov (Expand Search)
petroov » peteroov (Expand Search), petrioov (Expand Search), petrooov (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 petrioiov) OR (((((petroov OR petero) OR petru) OR perov) OR peri) OR petr)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriov OR petrioiov) OR (((((petroov OR petero) OR petru) OR perov) OR peri) OR petr)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriov OR petrioiov) OR (((((petroov OR petero) OR petru) OR perov) OR peri) OR petr)) o.s.*.