Let's assume that 10 empirical studies have been done for topic x. If I want to mention the following: Several studies have been conducted to deal with topic x (study 1; study 2; study 3).
My question: when I mention the word 'several', am I obligated to cite ALL the 10 empirical studies in the citation? Can I just cite a few? Should I use 'for example' to tell the reader that I am citing only 3 related studies, however others studies do exist?
If you doubt that a study should be included in the bibliography, then probably you don't consider it worth citing. Make a selection and then include every one of them in the bibliography. In the body you could say something like, "An exhaustive body of empirical studies exists on this topic [see: Study 1, Study 2,... Study N]. In particular, [Study X, Study Y] are most relevant to our work...".
Not including cited work in bibliography will be considered at best a sign of laziness and at worst an indication of unethical behaviour.