To see products for your region, visit the EU site?
Example Entry (Typical):
For the vintage repair enthusiast: Hunt for used copies of:
For the professional engineer: Skip the book. Bookmark NTE’s online cross-reference and master parametric search on DigiKey or Mouser.
For the student/hobbyist: Download the free "Transistor Cross-Reference Guide" PDF from various electronics archives (search: "transistor cross reference PDF site:archive.org").
At its core, a transistor equivalent book is a cross-reference guide. It lists thousands of original manufacturer part numbers (e.g., 2N2222, BC547, 2SC945) and suggests one or more substitute parts with similar electrical characteristics.
A good substitution must match or exceed the original in at least these key parameters:
Several paid and free apps (e.g., "Transistor Database," "Electronics ToolKit") have digitized old Towers and ECG databases. These are excellent for fieldwork. Search for "all transistor equivalent book app" in your app store.
For modern work, physical books are outdated as soon as they are printed. The "modern equivalent book" is a database. Here are the best tools: