6. A method as in claim 5 , wherein the parsing result includes a set of chosen sentences extracted from the textual reference material, each chosen sentence of the set of chosen sentences including an external fact; and wherein performing the parsing operation includes: separating the document into a group of sentences, and assigning a sentence of the group of sentences to be a chosen sentence of the set of chosen sentences when the sentence includes a keyword of a specified set of keywords.
5. A method as in claim 4 , wherein the document on the website to which the address corresponds includes textual reference material; and wherein extracting the external facts from the document includes: performing a parsing operation on the textual reference material of the document, the parsing operation being constructed and arranged to produce a parsing result; and obtaining the external facts from the parsing result.