Dualizing cartesian and cocartesian fibrations
  In this technical note, we proffer a very explicit construction of the "dual cocartesian fibration" $p^{\vee}$ of a cartesian fibration $p$, and we show they are classified by the same functor to $\mathbf{Cat}_{\infty}$. 
Clark Barwick and Saul Glasman and Denis Nardin
math.CT math.AT