Cartesian fibrations and representability

We use the complete Segal approach to theory of Cartesian fibrations define and study representable fibrations, generalizing right which have played a key role in $\infty$-category theory. In particular, we give construction using over-categories prove Yoneda lemma for fibration, generalizes established fibrations. We then objects internal an $\infty$-category. Concretely, {\it fundamental theorem objects}, characterizes equivalences objects. Finally two application results. First, present method construct second representability universal coCartesian fibration.