  The gravitational radiation from compact pulsar-like stars depends on the
state of dense matter at supranuclear densities, i.e., the nature of pulsar
(e.g., either normal neutron stars or quark stars). The solid quark star model
is focused for the nature of pulsar-like compact objects. Possible
gravitational emission of quark stars (either fluid or solid) during the birth
and later lifetime is discussed. Several observational features to distinguish
various models for pulsar-like stars are proposed. It is suggested that the
gravitational wave behaviors should be mass-dependent. Based on the data from
the second LIGO science run, the upper limits of R.theta^{1/5} and thus
M.theta^{3/5} (M: mass, R: radius, and theta: wobble angle) are provided for
those targets of millisecond pulsars.
