classifications
| search classifications for: Zhang Heng |
Scientists, early (18th-c and before) and general, philosophers of science, science advisors, popularisers, historians
Inventors
China, Hong Kong
Astronomers, astrophysicists, origins of universe theorists, radio engineers
Earthquakes
Measuring devices and devisers, direction indicators, units used in technology, inventors of measuring instruments
Cartography and cartographers
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