‘must reads’ of ~~contemporary~~ sociology

I missed 'contemporary' in your question and instead wrote about 'the classics' of sociology. I will still post the comment as is, as it might be informative to others, and make another one on contemporary sociology.

Émile Durkheim

... established the research methods of the social sciences. His other main work regards the cohesion of modern society as a consequence of interdependence through the division of labor as opposed to pre-modern societies, which were more 'mechanical' in their solidarity through concepts of kinship, religion and authority.

Max Weber

... lays the foundation of sociology by defining what sociology even investigates, by coining the term social acting, a concious act that is in reaction to the behavior of somebody else.

Karl Marx

... is most famous for his dialectic on class struggle, explaining social change as a phenomenon of class struggle between an upper class and a lower class, with the upper class always eventually being subverted by the limitations and consequences of the nature of their specific power base over the lower class.

Pierre Bourdieu

... expanded the concept of capital into non-economic areas by dividing it into economic, social, cultural and symbolic capital and then used this to explain social stratification and classification through the distributions of those forms of capital over social classes. He is also the father of a lot of other sociological concepts, like field theory.