About: http://webisa.webdatacommons.org/364460962

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	I do not know on VB.net but on c# you can wrap value types to be nullables using the ?, like:
http://www.w3.org/ns/prov#wasQuotedFrom	stackoverflow.com