Perhaps you should try some spelling variations:
petrv » petrov (Expand Search), petru (Expand Search), petro (Expand Search), peterv (Expand Search), petruv (Expand Search)
petri » peteri (Expand Search), petrui (Expand Search), petroi (Expand Search)
petrooi » peterooi (Expand Search), petruooi (Expand Search), petroooi (Expand Search)
petr » peter (Expand Search), petru (Expand Search), petro (Expand Search)
petriov » peteriov (Expand Search), petruiov (Expand Search), petroiov (Expand Search), petrov (Expand Search)
petruv » peteruv (Expand Search), petruuv (Expand Search), petrouv (Expand Search), petru (Expand Search), petrov (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 ((petri OR (petrv OR petrooi)) OR (petr OR (((peterov OR petriov) OR petruv) OR petri))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petri OR (petrv OR petrooi)) OR (petr OR (((peterov OR petriov) OR petruv) OR petri))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petri OR (petrv OR petrooi)) OR (petr OR (((peterov OR petriov) OR petruv) OR petri))) o.s.*.