About: http://webisa.webdatacommons.org/251502154

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 prisoners also used subtle cues, such as including certain words or underlining their signature, to signal to British intelligence that a letter contained coded information.
http://www.w3.org/ns/prov#wasQuotedFrom	publicradiotulsa.org