There are endless amount of tutorials available how to cite literature in different software. The Latex community has the \cite{} command while Lyx users can select the reference from a gui menu and in Word there is a plugin available for endnote or citavi. The surprising situation is, that even the citation can be created in this way some important information is missing. It is about why a certain citiation is inserted into the text and why not?
What most tutorials about academic writings are ignoring or explaining only as a side note is, that the source of each reference is not the database in the library and it is not google scholar but the source is always the personal knowledge management software. That means, an author has created his individual bibliographic database which looks different from a public database like google scholar.
Some programs for creating such databases are: jabref, bibtex, Obsidian, Zotero and citavi. The important question is why such a database needs to be created if it contains the same information like Google scholar? Wouldn't it make sense to cite directly from google scholar?
No because the inbetween layer is the personal note file of the user. During reading of books and papers, the user makes personal notes and in this notes the references were written down. During writing the prose text, the user has it's personal notes in a separate window and is citing from these notes the books. That means, a user doesn't cite a random book which may fit to the subject, but the user has to cite a book which is already in the own note file.
Suppose the citavi software was used to create notes. Then the newly written document gets enriched with bibliography references from this citavi file. And suppose the user prefers an Analog Zettelkasten in the style of Niklas Luhmann, then the references are taking from this note taking system.
This might explain why most authors are creating an individual reference database even they can use the normal database in a library or from google scholar. Because it is about making notes and the references are a part of this attempt. Let us imagine a counter example.
Suppose somebody hasn't created notes and has no personal bibliographic database. Then it is not allowed to cite anything. The unwritten rule is, that a citation can only be created if it is stored in the personal notes already. Otherwise, the user hasn't read a book and hasn't made notes about the book. So it makes no sense to cite it in the own paper.
If an academic paper has endless amount of notes, then the author of this paper has made endless amount of notes. Note taking is the prestep towards citing literature in the own paper.