I am in a position where I am writing both more professional articles, and supplementary articles to undergraduates. The supplementary works is meant to prepare the students for the graduate courses. This is in mathematics, and analysis in particular. I want the notes to be self contained, and therefore I cite, or refer to proofs and further discussions on the lemmas and corollaries that are used. This should also be used for further references, "if you want to know more about metric spaces, please look at Kreyszig ".
I have a wide variety of books I can cite, I can pick any of the big books used in Calculus. Calculus by Adams etc Calculus: Early Transcendentals by James Stewart. On the other hand I could refer to the more classical works by Apostol or Rudin (Principles of mathematical analysis)
Choosing the more classical works is good for preping the stundents, but for a first touch these can be a bit terse. Also the proofs in for an example Rudin are a bit on the short side, whilst Adams is very wordy Would citing both, for every lemma and theorem, make the citations too daunting?
Long story short:
When should one cite the terse material, and when to choose the lengthier comprehensible works. How does one choose the appropriate level to cite from when writing an article, paper or notes ?