Assertion: historian | /r/CapableOf | use the phrase
Facets:
value: to refer to the original documents
type: PURPOSE
value: sometimes
type: TEMPORAL
Source sentences:
text: Historians sometimes use the phrase "primary sources" to refer to the original documents that provide the building blocks for everything we know about the past.
text: They use the phrase "secondary sources" to refer to the writings of scholars and other people who have used primary documents to interpret the past.