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12 Novels Considered the “Greatest Book Ever Written”

A Factory Interior, watercolor, pen and gray ink, graphite, and white goache on wove paper by unknown artist, c. 1871-91; in the Yale Center for British Art. Industrial Revolution England

Inventors and Inventions of the Industrial Revolution

Leonardo da Vinci (1452-1519), Italian Renaissance painter from Florence. Engraving by Cosomo Colombini (d. 1812) after a Leonardo self portrait. Ca. 1500.

10 Famous Artworks by Leonardo da Vinci

Los Angeles Police Department wanted flyer on Elizabeth Short, aka the "Black Dahlia," who was brutally murdered in January 1947. The FBI supported the Los Angeles Police Department in the case, including by identifying Short through her fingerprints that

America’s 5 Most Notorious Cold Cases (Including One You May Have Thought Was Already Solved)

Title: Senate Square, St. Petersburg, December 14, 1825: repression of the troop mutiny - watercolor by Carl Ivanovitch Kollman, 1825 depicts Decembrist uprising clashing with cavalry, with spectators watching. (new style December 26, 1825) Europe. Saint

8 of the Largest Empires in History

Woman tied to a ducking stool, a method of punishment by means of humiliation, beating, or death. (cucking stool)

8 Unusual Punishments Inflicted on Women Throughout History

A human Inuit skull in a stone chambered cairn in Ilulissat in Greenland. These ancient graves are pre christian and are at least 2000

14 Tough Questions Answered

blackhead

acne

Also known as: comedo, comedones

Learn about this topic in these articles:

primary lesion of acne

In acne
…vulgaris is the comedo, or blackhead, which consists of a plug of sebum (the fatty substance secreted by a sebaceous gland), cell debris, and microorganisms (especially the bacterium Propionibacterium acnes) filling up a hair follicle. Comedones may be open, their upper or visible portion being darkened by oxidative changes, or…
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