  We present results from a study of the non-nuclear discrete sources in a
sample of three nearby spiral galaxies (NGC 4395, NGC 4736, and NGC 4258) based
on XMM-Newton archival data supplemented with Chandra data for spectral and
timing analyses. A total of 75 X-ray sources has been detected within the D25
regions of the target galaxies. The large collecting area of XMM-Newton makes
the statistics sufficient to obtain spectral fitting for 16 (about 20%) of
these sources. Compiling the extensive archival exposures available, we were
able to obtain the detailed spectral shapes of diverse classes of point
sources. We have also studied temporal properties of these luminous sources. 11
of them are found to show short-term (less than 80 ks) variation while 8 of
them show long-term variation within factors of ~ 2 to 5 during a time interval
of ~ 2 to 12 years. Timing analysis provides strong evidence that most of these
sources are accreting X-ray binary (XRB) systems. One source that has
properties different than others was suspected to be a Supernova Remnant (SNR),
and our follow-up optical observation confirmed it. Our results indicate that
sources within the three nearby galaxies are showing a variety of source
populations, including several Ultraluminous X-Ray Sources (ULXs), X-ray
binaries (XRBs), transients together with a Super Soft Source (SSS) and a
background Active Galactic Nucleus (AGN) candidate.
