this might be a stupid question, but I am asking this in particular as a non-native speaker of English. Given that we all (even native speakers) will get our English expressions from somewhere, I am wondering when a citation/quotation becomes necessary if one finds a useful academic expression in other writings and wishes to use that in one's own writing. To be clear I am not talking here about a) original ideas that one borrows b) whole sentences or long phrases. Rather, I am thinking of expressions/wordings/language that I (again as a non-native speaker) would think are common or logical enough that they would not warrant citation/quotation.

An example could be "I wish to acknowledge the excellent research assistance" in the acknowledgements of an article.

The same goes for using other writings as a model. I am again not talking here of taking over the whole structure of a piece. Rather, I am, for instance, thinking about reading the conclusions of other theses to understand how to write a conclusion in terms of structure etc.