  The ionization losses -- the losses of energy by fast charged particles
traveling through a matter -- have been under study for more than 100 years.
The theoretical explanation of this process spans similar period. About 75
years ago, Lev Landau published a theoretical paper on the ionization losses,
which drastically leveled up the research and still remains amongst the most
cited in the field. The present note digests the history of theoretical
development and attempts to clarify Landau's method of research and the
function named after him.
