http://book.klll.cc/ebooks/subject/3910.opds?sort_order=release_date 2025-08-10T08:49:32Z Books about Number concept (sorted by release date) Free eBooks since 1971. Project Gutenberg https://book.klll.cc webmaster@gutenberg.org https://book.klll.cc/gutenberg/favicon.ico 25 1 2025-08-10T08:49:32Z https://book.klll.cc/ebooks/subject/3910.opds?sort_order=title Sort Alphabetically by Title 2025-08-10T08:49:32Z https://book.klll.cc/ebooks/subject/3910.opds?sort_order=downloads Sort by Popularity 2025-08-10T08:49:32Z https://book.klll.cc/ebooks/48312.opds Die Grundlagen der Arithmetik (German) Gottlob Frege 2025-08-10T08:49:32Z https://book.klll.cc/ebooks/16449.opds The Number Concept: Its Origin and Development Levi L. Conant