Verified70% confidenceFactTime unknown
German sociologist Niklas Luhmann produced over 70 books and 400 papers over 40 years using approximately 90,000 mutually cross-referenced index cards.
4
Sources
70%
Confidence
Long-term
Relevance
5/31/2026
First Seen
Sources
Related Entities
Related Claims
UnverifiedIn 1931, a book titled Hundert Autoren gegen Einstein (A Hundred Authors Against Einstein) was published in Germany, in which a hundred authors jointly attempted to refute Einstein's theory of relativity.57% similarUnverifiedThe European Union's standard for determining public domain status is 70 years after the author's death.56% similarUnverifiedThe Zettelkasten method was developed by German sociologist Niklas Luhmann.54% similarUnverifiedMichael Watkins's 'The First 90 Days' was listed by Fortune magazine as one of '25 Business Books Every Leader Must Read.'54% similar
Cite This Claim
Stable URI
https://kongchang.com/claim/8057API
curl https://kongchang.com/api/v1/knowledge/claims/8057MCP
get_claim(id=8057)