Perhaps you should try some spelling variations:
petrie » petri (Expand Search), patrie (Expand Search), petre (Expand Search), petriie (Expand Search), petroie (Expand Search), perie (Expand Search)
petris » petri (Expand Search), petriis (Expand Search), petrois (Expand Search), peris (Expand Search)
petr » petri (Expand Search), petro (Expand Search), per (Expand Search)
petriov » petriiov (Expand Search), petroiov (Expand Search), periov (Expand Search), petrov (Expand Search)
petru » petriu (Expand Search), petrou (Expand Search), peru (Expand Search), petri (Expand Search)
petrooi » petriooi (Expand Search), petroooi (Expand Search), perooi (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 ((((petrie OR petris) OR petr) OR petriov) OR (((petru OR pentru) OR petrooi) OR peter)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop ((((petrie OR petris) OR petr) OR petriov) OR (((petru OR pentru) OR petrooi) OR peter)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop ((((petrie OR petris) OR petr) OR petriov) OR (((petru OR pentru) OR petrooi) OR peter)) o.s.*.