Perhaps you should try some spelling variations:
petris » petri (Expand Search), petriis (Expand Search), petruis (Expand Search), petrois (Expand Search)
peters » petersen (Expand Search)
petriov » petrov (Expand Search), petriiov (Expand Search), petruiov (Expand Search), petroiov (Expand Search)
petruis » petriuis (Expand Search), petruuis (Expand Search), petrouis (Expand Search)
petruuiiiov » petriuuiiiov (Expand Search), petruuuiiiov (Expand Search), petrouuiiiov (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 ((petris OR petruis) OR ((peters OR (petriov OR petruuiiiov)) OR (petr OR peter))) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((petris OR petruis) OR ((peters OR (petriov OR petruuiiiov)) OR (petr OR peter))) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((petris OR petruis) OR ((peters OR (petriov OR petruuiiiov)) OR (petr OR peter))) o.s.*.