Waldmann, H., Khedkar, V., Dückert, H., Schürmann, M., Oppel, I. M., & Kumar, K. (2008). Asymmetric Synthesis of Natural Product Inspired Tricyclic Benzopyrones by an Organocatalyzed Annulation Reaction. Angewandte Chemie, 120(36): 1, pp. 6975-6978. Retrieved from http://dx.doi.org/10.1002/ange.200802413.