Sources are classified according to primary, secondary and
- Primary sources
are original materials. Examples of these are reports, magazine articles,
patents, theses, dissertations, manuscripts, monographs.
- Secondary sources
are materials prepared from original or primary sources. Original
materials which have been rearranged, interpreted, condensed, belong
to this classification.
- Tertiary sources
are primary and secondary sources combined together. These are materials
that have been twice removed from the original. Almost all types of
reference sources fall under this classification.
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