The web can be found here https://gordonhoklinder.github.io/sequence-calculus/.
I've chosen the topic of sequence calculus for this book because I've found it to be an intriguing topic not many people are aware of. However, I'm no pro, therefore if you find a mistake, feel free to raise an issue or create a pull request.
So far there are only two chapters, but I might write more in the future.
This simple static web was made for the Introduction to Networking courses at the Charles University.