The 'Angiosperm Phylogeny Group' system of flowering plant  classification (APG,  1998. An ordinal Classification for the Families of Flowering Plants.  Annals of the Missouri Botanical Garden 85:  531-553) organizes flowering plants into a "selected number of monophyletic suprafamilial groups".  The three most inclusive groups are here placed, for comparative purposes, as classes (see discussion).
    Eudicots Neither     Monocots
Not Commelinoids
Core Eudicots
      Probably Eudicots

Internet information for a given family can be obtained by browsing its 'group' page (listed above) or, by using the family finder, which provides alphabetical selection of the family name and direct placement on the appropriate Subclass page of the Cronquist classification system.