When I learn stuff, I record identifiable sources in a catalog using the Universal Decimal Classification system. Thus I have stats on my recorded 2025 nonfiction study areas. Like:
• My most common "main class" in 2025 was "MATHEMATICS. NATURAL SCIENCES".
• My most common 2025 "subclasses"—not limited only to the "main class" above—were "Mathematics", "Prolegomena. Fundamentals of knowledge and culture. Propaedeutics", "Physics", "Astronomy. Astrophysics. Space research. Geodesy", and "Medical sciences".
• I recorded four of six possible nonfiction media types in 2025, mostly consisting of articles, with 88 percent frequency, and books (or their equivalents), with 11 percent frequency.
In case you're considering producing such a catalog, I will tell you that an acceptable alternative to the Universal Decimal Classification system is the Library of Congress Classification system. Play around with both systems, and take your pick. However, the Dewey Decimal Classification system is not an acceptable alternative.
#learning
#UDC
#UniversalDecimalClassification