About: http://webisa.webdatacommons.org/74947027

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	The surface needs to be flat and next to a wall or other large surface perpendicular to it.
http://www.w3.org/ns/prov#wasQuotedFrom	sciencebuddies.org