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1 · Religion and Magic
2 · Nature
3 · Human Being, Man in General
4 · Society, Civilization, Culture
5 · Abstract Ideas and Concepts
6 · History
7 · Bible
8 · Literature
9 · Classical Mythology and Ancient History
Top
4 · Society, Civilization, Culture
49 · education, science and learning
49E · science and technology
49E2 · physics and mechanics
49E25 · optics
49E251 · optical instruments
49E252 · refraction (optics)
49E253 · prism (optical instrument)
49E254 · concave mirror, burning-mirror
49E255 · magnification
49E25(+7) · optics (+ basic phenomena and processes in the natural sciences)
2 available