Does the stellar disc flattening depend on the galaxy type?
  We analyze the dependence of the stellar disc flatness on the galaxy
morphological type using 2D decomposition of galaxies from the reliable
subsample of the Edge-on Galaxies in SDSS (EGIS) catalogue. Combining these
data with the retrieved models of the edge-on galaxies from the Two Micron All
Sky Survey (2MASS) and the Spitzer Survey of Stellar Structure in Galaxies
(S$^4$G) catalogue, we make the following conclusions:
  (1) The disc relative thickness $z_0/h$ in the near- and mid-infrared
passbands correlates weakly with morphological type and does not correlate with
the bulge-to-total luminosity ratio $B/T$ in all studied bands.
  (2) Applying an 1D photometric profile analysis overestimates the disc
thickness in galaxies with large bulges making an illusion of the relationship
between the disc flattening and the ratio $B/T$.
  (3) In our sample the early-type disc galaxies (S0/a) have both flat and
"puffed" discs. The early spirals and intermediate-type galaxies have a large
scatter of the disc flatness, which can be caused by the presence of a bar:
barred galaxies have thicker stellar discs, on average. On the other hand, the
late-type spirals are mostly thin galaxies, whereas irregular galaxies have
puffed stellar discs.
