Perhaps you should try some spelling variations:
petra » petro (Expand Search), petre (Expand Search), petera (Expand Search), petroa (Expand Search), pera (Expand Search)
peteroe » petersen (Expand Search)
petris » peteris (Expand Search), petrois (Expand Search), peris (Expand Search)
petroois » peteroois (Expand Search), petrooois (Expand Search), peroois (Expand Search)
petr » peter (Expand Search), petro (Expand Search), per (Expand Search)
petru » peteru (Expand Search), petrou (Expand Search), peru (Expand Search), pentru (Expand Search)
petrou » peterou (Expand Search), petroou (Expand Search), perou (Expand Search), petro (Expand Search), petrov (Expand Search), petrow (Expand Search)
petri » peteri (Expand Search), petroi (Expand Search), peri (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 petroois) OR ((petra OR peteroe) OR petr)) OR ((petru OR petrou) OR petri)) o.s.~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "fop (((petris OR petroois) OR ((petra OR peteroe) OR petr)) OR ((petru OR petrou) OR petri)) o.s.".
• Adding a wildcard symbol may retrieve word variants: fop (((petris OR petroois) OR ((petra OR peteroe) OR petr)) OR ((petru OR petrou) OR petri)) o.s.*.