  We construct the universal enveloping preassociative and postassociative
algebra for a pre-Lie and a postLie algebra respectively. We show that the
pairs $(\mathrm{preLie},\mathrm{preAs})$ and
$(\mathrm{postLie},\mathrm{postAs})$ are Poincare-Birkhoff-Witt-pairs, for the
first one it's a reproof of the result of V. Dotsenko and P. Tamaroff.
