I am a new teacher/lecturer in science, and I am preparing lecture notes for my module. I am putting together a lot of material coming from textbooks as well as borrowing material from other lecture notes I come across online. In the bibliography, I have included the main textbooks, as students are encouraged to read them and try some of the exercises in those books. However, I am not sure how, or if I should, include references to the material I am taking from other lecture notes. First, if I include too many references, it will be useless for the students. Second, the material in those lecture notes is not original either. What are some general rules and guidelines for citing material in your lecture notes?
There are three different sorts of bibliographic entries in your situation, I think: suggestions for further reading (for the students), acknowledgement of your sources, and historical references. One should acknowledge one's sources, whether or not it "helps the students". I think it will help them in the larger sense of perhaps slightly better appreciating how human knowledge is advanced and organized. Including historical references helps people understand the timescale on which things happen.
Even with "well-known" relatively elementary results whose origins have faded into obscurity, you can note that you learned these things from various textbooks yourself... not that you came up with it all yourself, for example. You could tell the textbooks you studied from.
Even if that information is not "tested-on", I think it sets a good model for the students.
There’s nothing preventing you from compiling two entirely separate bibliographies, under separate section headers: One with highlights/seminal works (“these are worth skimming”), and one detailed bibliography for individual claims and sources.
A few popular science books and textbooks do that and it’s a huge benefit to the reader: if you managed to stir the students’ interest, many will peruse the reading list out of curiosity. By contrast, few (if any) will read through the detailed bibliography (who even does that?) but if somebody needs to follow up on an individual reference, it’s there.