It depends on where you are
For example, in USA copyright exists in a literary or artistic work stored in permanent form like a book, a movie, an audio recording, a building etc.
In contrast, in Australia there is no requirement for the work to be stored - that means copyright can exist in a spoken lecture.
The owner of the copyright (usually, but not necessarily the creator) has the right to choose if and how their work is copied and if and how any derivative works may be made from it.
For your example, the book is an original work in which copyright vests with the author(s), your notes are a derivative work in which copyright vests in you.
However, you presumably did not have permission to make your derivative work so that makes it prima facie a copyright infringement.
Fortunately, in the USA there exists a Fair Use defence and in Commonwealth countries the slightly less permissive Fair Dealing defence (if you are somewhere else you will need to do your own research). Search this site or read the copyright article on Wikipedia to learn about these defences.
Long answer short (too late!), taking notes to aid your own study is almost certainly Fair Use/Dealing. So is sharing it with your friends. Publishing it may or may not be depending on all sorts of factors; for example, if you were to write a study guide for say a Harry Potter book for use by English literature students this is probably OK even if it is a for profit activity, because criticism is Fair Use/Dealing.
Citing work is not necessary to comply with copyright law. Failing to cite may be academic misconduct but that is not a legal matter; its a matter for your academic institution.
