Perhaps you should try some spelling variations:
petriov » petrov (Expand Search), petriiov (Expand Search), petruiov (Expand Search), petroiov (Expand Search)
petrii » petri (Expand Search), petris (Expand Search), petriii (Expand Search), petruii (Expand Search), petroii (Expand Search)
petrou » petru (Expand Search), petro (Expand Search), petrov (Expand Search), petriou (Expand Search), petruou (Expand Search), petroou (Expand Search)
petruou » petriuou (Expand Search), petruuou (Expand Search), petrouou (Expand Search)
petr » petri (Expand Search), petru (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 ((perui OR petrii) OR (petrou OR petruou))) OR (petr OR peter)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petriov OR ((perui OR petrii) OR (petrou OR petruou))) OR (petr OR peter)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petriov OR ((perui OR petrii) OR (petrou OR petruou))) OR (petr OR peter)) o.s.*.