https://archive.org/details/britannica_propaedia/mode/2up

The one-volume Propædia is the first of three parts of the 15th edition of Encyclopædia Britannica, the other two being the 12-volume Micropædia and the 17-volume Macropædia. The Propædia is intended as a topical organization of the Britannica's contents, complementary to the alphabetical organization of the other two parts. Introduced in 1974 with the 15th edition, the Propædia and Micropædia were intended to replace the Index of the 14th edition; however, after widespread criticism, the Britannica restored the Index as a two-volume set in 1985. ==The core of the Propædia is its Outline of Knowledge, which seeks to provide a logical framework for all human knowledge==; however, the Propædia also has several appendices listing the staff members, advisors and contributors to all three parts of the Britannica.

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