The 2 Columbia Masters sets (c. unknown) and Music Appreciation Recordings set(c.1941) are about 3/16" thick and one of the albums has a little ding on the edge and is starting to delaminate but the damage doesn't extend into the play area. I'm about 99% certain that these are 78s.

The China Records set is actually thinner than most of the 70's to 80's LPs I've handled. They say 33 1/3 on the label. The interesting thing about them is they have liner notes??? (18 loose pages) in Chinese.