  We considered a graphene nano-ribbon with a longitudinal electric field
(along $x$ direction) and a transversal magnetic field (along $z$ direction),
and then observe (i) the electrocaloric effect ruled by an applied magnetic
field and (ii) the magnetocaloric effect ruled by an applied electric field. We
focused our attention to the limit of low temperatures, and then observed
interesting step-like features. For each filled Landau level $n$, created by
the applied magnetic field, both caloric effects increase proportionally to
$n+1/2$; and this step measures either important graphene properties (like
Fermi velocity) or quantum fundamental quantities (like Planck constant and
magnetic flux quantum).
