Perhaps you should try some spelling variations:
"put–hcall parity" » "put–call parity", "put–call arity", "put–health parity", "put–hccall parity", "put–hcall party", "put–hcall parts"
"put–hall parity" » "put–call parity", "put–hall part", "put–hall patrick", "put–hcall parity", "put–hall party", "put–hall parts"
"put–all parity" » "put–call parity", "put–all party", "put–all parts"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("put–all parity") OR ((("put–hall parity") OR ("put–hcall parity")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"put–all parity\") or (((\"put–hall parity\") OR (\"put–hcall parity\"))))".
• Removing quotes may allow a broader search: (( put–all parity ) or ((( put–hall parity ) OR ( put–hcall parity )))).
• Adding a wildcard symbol may retrieve word variants: (("put–all parity") or ((("put–hall parity") OR ("put–hcall parity"))))*.