About: http://webisa.webdatacommons.org/113872256

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	So, yes, they are there, in fact, you cannot -- some of the examples are remarkable, including the ones that you mentioned.
http://www.w3.org/ns/prov#wasQuotedFrom	chomsky.info