General historical materials are divided into first-class historical materials. Source) and second-hand historical materials (second-hand? Source).
The former refers to the historical materials that are close to or directly generated from the time when history occurred, which can be used as the historical basis more directly, while the latter refers to the research and interpretation made by later generations using first-hand historical materials, but the boundary between the two is often not clear (for example, Historical Records can hardly be said to be first-hand or second-hand historical materials).
Generally speaking, the historical materials in Chinese mainly refer to the first-hand historical materials.
I think references are more formal, official and written than historical materials.
Historical materials can be divided into four categories, which is generally considered to be a more comprehensive and reasonable classification of traditional historical materials.
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The first category is books and newspapers, including historical records, historical works, document compilation and group members outside the history department.
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The second category is documents, including * * * documents, group documents and private documents.
The third category is physical objects, including production tools, means of subsistence and relics of historical events.
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The fourth category is word of mouth, including memoirs, investigation records, mass legends and literary works.
Reference is the whole reference or quotation of a book or a paper in the process of academic research.
The cited documents have been noted in the notes and no longer appear in the following references.