Uniqueness of A_infty-structures and Hochschild cohomology

This paper investigates if a differential graded algebra can have more than one $A_\infty$-structure extending the given differential graded algebra structure. We give a sufficient condition for uniqueness of such an $A_\infty$-structure up to quasi-isomorphism using Hochschild cohomology. We then extend this condition to Sagave's notion of derived $A_\infty$-algebras after introducing a notion of Hochschild cohomology that applies to this.