  We calculate the spectrum of $q\bar q c \bar c$ and $s\bar s c \bar c$
tetraquarks, where $q$, $s$ and $c$ stand for light ($u,d$), strange and charm
quarks, respectively, in a relativized diquark model, characterized by
one-gluon-exchange (OGE) plus confining potential. In the diquark model, a
$q\bar q c \bar c$ ($s\bar s c \bar c$) tetraquark configuration is made up of
a heavy-light diquark, $q c$ ($sc$), and anti-diquark, $\bar q \bar c$ ($\bar s
\bar c$). According to our results, 13 charmonium-like observed states can be
accommodated in the tetraquark picture, both in the hidden-charm ($q\bar q c
\bar c$) and hidden-charm hidden-strange ($s\bar s c \bar c$) sectors.
