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?