Perhaps you should try some spelling variations:
"exogenous dinitrogen sulfide" » "exogenous estrogens sulfide", "exogenous androgens sulfide", "exogenous antigen sulfide", "exogenous nitrogen disulfide"
"endogenous estrogen sulfide" » "exogenous estrogens sulfide", "endogenous hydrogen sulfide", "endogenous pyrogen sulfide", "endogenous nitrogen sulfide", "endogenous nitrogen disulfide"
"exogenous estrogen sulfide" » "exogenous estrogens sulfide", "exogenous nitrogen sulfide", "exogenous hydrogen sulfide", "exogenous nitrogen disulfide"

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"endogenous estrogen sulfide\") OR (((\"exogenous estrogen sulfide\") OR (\"exogenous dinitrogen sulfide\"))))".
• Removing quotes may allow a broader search: (( endogenous estrogen sulfide ) OR ((( exogenous estrogen sulfide ) OR ( exogenous dinitrogen sulfide )))).
• Adding a wildcard symbol may retrieve word variants: (("endogenous estrogen sulfide") OR ((("exogenous estrogen sulfide") OR ("exogenous dinitrogen sulfide"))))*.