http://book.klll.cc/ebooks/subject/3910.opds?sort_order=downloads 2025-08-09T15:41:16Z Books about Number concept (sorted by popularity) Free eBooks since 1971. Project Gutenberg https://book.klll.cc webmaster@gutenberg.org https://book.klll.cc/gutenberg/favicon.ico 25 1 2025-08-09T15:41:16Z https://book.klll.cc/ebooks/subject/3910.opds?sort_order=title Sort Alphabetically by Title 2025-08-09T15:41:16Z https://book.klll.cc/ebooks/subject/3910.opds?sort_order=release_date Sort by Release Date 2025-08-09T15:41:16Z https://book.klll.cc/ebooks/16449.opds The Number Concept: Its Origin and Development Levi L. Conant 2025-08-09T15:41:16Z https://book.klll.cc/ebooks/48312.opds Die Grundlagen der Arithmetik (German) Gottlob Frege