Key points are not available for this paper at this time.
Richard G. Olmstead, Helen J. Michaels, Kathy M. Scott, Jeffrey D. Palmer, Monophyly of the Asteridae and Identification of Their Major Lineages Inferred From DNA Sequences of rbcL, Annals of the Missouri Botanical Garden, Vol. 79, No. 2 (1992), pp. 249-265
Olmstead et al. (1992) studied this question.