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