Book references about continued fractions

Question

I'm searching for one or more books about continued fractions which covers these aspects:

1. An introductory level book about continued fractions.
2. A divulgative book about continued fractions with some historical background on how and when continued fractions were discovered. (These can be two books, each covering one of the two aspects.)
3. A book (article or something related) about didactic with continued fractions.

Any suggestion will be very appreciated.

Answer 1

Continued Fractions, by C. D. Olds was my first book on the topic (in high school, I think?), and I was hooked.

Answer 2

I enjoyed Continued Fractions by A. Ya. Khinchin. It's very short and clear.

Part I covers the elementary results that everyone ought to know.

Part III is about the measure theory of continued fractions: For example, pick a number at random from an interval; what's the probability that its CF expansion contains a 3 somewhere? This theory leads to the surprising result that the geometric mean of the partial denominators has the same value, about $2.6854$, for nearly all numbers.

Inexpensive copies are widely available. The current Dover edition costs US$8.95.