  Cool white dwarfs with Teff < 6000 K are the remnants of the oldest stars
that existed in our Galaxy. Their atmospheres, when properly characterized, can
provide valuable information on white dwarf evolution and ultimately star
formation through the history of the Milky Way. Understanding the atmospheres
of these stars requires joined observational effort and reliable atmosphere
modeling. We discuss and analyze recent observations of the near-ultraviolet
(UV) and near-infrared (IR) spectrum of several cool white dwarfs including
DQ/DQp stars showing carbon in their spectra. We present fits to the entire
spectral energy distribution (SED) of selected cool stars, showing that the
current pure-hydrogen atmosphere models are quite reliable, especially in the
near-UV spectral region. Recently, we also performed an analysis of the coolest
known DQ/DQp stars investigating further the origin of the C2 Swan bands-like
spectral features that characterize the DQp stars. We show that the carbon
abundances derived for DQp stars fit the trend of carbon abundance with Teff
seen in normal cool DQ stars. This further supports the recent conclusion of
Kowalski A&A (2010) that DQp stars are DQ stars with pressure distorted Swan
bands. However, we encounter some difficulties in reproducing the IR part of
the SED of stars having a mixed He/H atmosphere. This indicates limitations in
current models of the opacity in dense He/H fluids.
