Perhaps you should try some spelling variations:
petriov » petrov (Expand Search), peteriov (Expand Search), petruiov (Expand Search), petroiov (Expand Search)
petriv » petris (Expand Search), petrov (Expand Search), peteriv (Expand Search), petruiv (Expand Search), petroiv (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (Expand Search)
petrou » peterou (Expand Search), petruou (Expand Search), petroou (Expand Search), petru (Expand Search), petro (Expand Search), petrov (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (Expand Search)
peters » peter (Expand Search), petersen (Expand Search)
peterov » petrov (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 petriv) OR ((((petr OR petrou) OR peters) OR peterov) OR (petri OR per))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriov OR petriv) OR ((((petr OR petrou) OR peters) OR peterov) OR (petri OR per))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriov OR petriv) OR ((((petr OR petrou) OR peters) OR peterov) OR (petri OR per))) o.s.*.