Systems-of-systems are formed through integration of individual complex systems, often not designed to work together. A number of factors can make this integration very challenging which often leads to catastrophic failures. In this paper, we focus on three major classes of system-of-system integration problems: managerial independence, interface incompatibility, and component-system complexity. We then present an aspect-oriented requirements description language (RDL) which uses natural language analysis capabilities to reason about dependencies across the documentation of the constituent systems of a system-of-systems. The aspect-oriented compositions in the RDL also facilitate specification of cross-document constraints and inconsistency resolution strategies, which can be used for deriving proof obligations and test cases for verification and validation of the emergent behaviour of a system-of-systems. We showcase the capabilities of our RDL through a case study of a real-world emergency response system. Our analysis shows that the querying and composition capabilities of the RDL provide valuable support for reasoning across documentation of multiple systems and specifying suitable integration constraints.