Encyclopedia Britannica - 15th edition, 1993, 32 volumes. complete set

The Encyclopædia Britannica is a general-knowledge English-language encyclopaedia. It has been published by Encyclopædia Britannica, Inc. since 1768, although the company has changed ownership seven times. The 2010 version of the 15th edition, which spans 32 volumes and 32,640 pages, was the last printed edition. 

Printed for 244 years, the Britannica was the longest-running in-print encyclopaedia in the English language. It was first published between 1768 and 1771 in Edinburgh, Scotland, in three volumes. The encyclopaedia grew in size; the second edition was 10 volumes,[2] and by its fourth edition (18011810), it had expanded to 20 volumes. Its rising stature as a scholarly work helped recruit eminent contributors, and the 9th (18751889) and 11th editions (1911) are landmark encyclopaedias for scholarship and literary style.