Perhaps you should try some spelling variations:
petriov » petrov (Expand Search), peteriov (Expand Search), petruiov (Expand Search), petroiov (Expand Search)
petruuv » peteruuv (Expand Search), petruuuv (Expand Search), petrouuv (Expand Search)
petriuv » peteriuv (Expand Search), petruiuv (Expand Search), petroiuv (Expand Search)
petruio » peteruio (Expand Search), petruuio (Expand Search), petrouio (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (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 ((petruuv OR peteruuv) OR petriuv)) OR (petruio OR (petr OR petri))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriov OR ((petruuv OR peteruuv) OR petriuv)) OR (petruio OR (petr OR petri))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriov OR ((petruuv OR peteruuv) OR petriuv)) OR (petruio OR (petr OR petri))) o.s.*.