An extremely good history of the important developments in typography in the last century. Anyone who has any interest in fonts and typography should read this book.
The home page of the Unicode organization, includes FAQs, glossary, new, character tables and the standard itself (in PDF).
PDF version of the book “Adobe Type 1
Font Format” (Addison-Wesley: 1990). This specification provides information on how PostScript Type 1 fonts are stored, and what hints can be provided by the font designer.
The official definition of the OpenType font format.