<http://webisa.webdatacommons.org/390875664>	<http://www.w3.org/ns/prov#wasQuotedFrom>	<umn.edu> .
<http://webisa.webdatacommons.org/390875664>	<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>	<http://www.w3.org/ns/prov#Entity> .
<http://webisa.webdatacommons.org/prov/361806125>	<http://www.w3.org/ns/prov#wasDerivedFrom>	<http://webisa.webdatacommons.org/390875664> .
<http://webisa.webdatacommons.org/390875664>	<http://www.w3.org/ns/prov#value>	"Determining what activities to include and what to exclude are the most difficult issues in developing a carbon calculator." .