  The phonon dispersion, density of states, Gr\"{u}neisen parameters, and the
lattice thermal conductivity of single- and multi-layered boron nitride were
calculated using first-principles methods. For the bulk {\it h}-BN we also
report the two-phonon density of states. We also present simple analytical
solutions to the acoustic vibrational mode-dependent lattice thermal
conductivity. Moreover, computations based on the elaborate Callaway-Klemens
and the real space super cell methods are presented to calculate the sample
length and temperature dependent lattice thermal conductivity of single- and
multi-layered hexagonal boron nitride which shows good agreement with
experimental data.
