I came across the following paper:
Weinhardt, C., A. Anandasivam, et al. (2009). “Cloud Computing – A Classification, Business Models, and Research Directions.” Business & Information Systems Engineering 1(5): 391-399.
The papers aim are to identify criteria to distinguish between Grids and Clouds. This is used to present business models ensuring Clouds sustainability. Finally the future of Cloud computing is mapped, suggesting relevant research directions. (P392).