Who is Nathan Glazer and Daniel Patrick Moynihan from The Hidden Dimension and what is their importance?

Co-authors of the book, Beyond the Melting Pot, Glazer and Moynihan clearly demonstrate that there is actually no "melting pot" in American cities, because ethnic groups maintain their own identities for generations. Hall uses the conclusions of their work to propose the construction of cultural/ethnic enclaves within urban areas, for social order and proxemic comfort of all groups.