Sources

Each course lists its own sources at the end of its units and in its source file. The main institutions and open materials used across the site are:

• Science: NASA, NOAA, USGS, NIST, IUPAC, NIH (NHGRI, NHLBI, MedlinePlus), OpenStax College Physics, Biology and Chemistry
• Maps: Natural Earth (public domain) for borders and coastlines
• History: British Museum, Metropolitan Museum of Art, Smithsonian, 국사편찬위원회 (National Institute of Korean History), Encyclopedia of Korean Culture
• Languages: RAE and Instituto Cervantes (Spanish), Académie française (French), 国家语言文字工作委员会 and the Ministry of Education of China (Chinese), Agency for Cultural Affairs of Japan (Japanese), National Institute of Korean Language (Korean), Cambridge and Merriam-Webster (English)
• Web and code: MDN Web Docs, WHATWG HTML, W3C CSS and WCAG, ECMAScript specification
• Music: Open Music Theory (CC BY-SA), public-domain melodies only
• Math and statistics: OpenStax algebra and statistics texts, MacTutor History of Mathematics
• Civics test: U.S. Citizenship and Immigration Services question lists (public domain)