  Recently, Balogh, Kostochka and Liu in [Packing chromatic number of cubic
graphs, Discrete Math.~341 (2018) 474--483] answered in negative the question
that was posed in several earlier papers whether the packing chromatic number
is bounded in the class of graphs with maximum degree $3$. In this note, we
present an explicit infinite family of subcubic graphs with unbounded packing
chromatic number.
