Just open the vmf file in a text editor:
world
{
"id" "1"
"skyname" "sky_hydro_01"
"maxpropscreenwidth" "-1"
"detailvbsp" "detail.vbsp"
"detailmaterial" "detail/detailsprites"
"mapversion" "520"
"comment" "Decompiled by BSPSource v1.3.20 from jump_elephant_a2"
"classname" "worldspawn"
solid
{
"id" "2"
side
{
"id" "3"
"plane" "(-2690 -192 880) (-2690 -192 512) (-2690 0 512)"
"smoothing_groups" "0"
"material" "wood/grain_elevator_facade_14a"
"uaxis" "[0 -1 0 -320] 0.25"
"vaxis" "[0 0 -1 -256] 0.25"
"lightmapscale" "24"
}
side
{
"id" "4"
"plane" "(-2306 0 880) (-2306 0 512) (-2306 -192 512)"
"smoothing_groups" "0"
"material" "wood/grain_elevator_facade_14a"
"uaxis" "[0 -1 0 -320] 0.25"
"vaxis" "[0 0 -1 -256] 0.25"
"lightmapscale" "24"
}
side
{
"id" "5"
"plane" "(-2306 -192 880) (-2306 -192 512) (-2690 -192 512)"
"smoothing_groups" "0"
"material" "wood/grain_elevator_facade_06"
"uaxis" "[-1 0 0 -328] 0.25"
"vaxis" "[0 0 -1 -256] 0.25"
"lightmapscale" "24"
}
...