S - This is on the floor at the bottom of the level.

T - This is inside the small tunnel thing at the bottom, it will be under the two boxes so you will have to destroy them to see it

A - This is on the eastern wall just below the first ring.

R - This is on the eastern wall just after the first ring, about half way up the wall.

D - This is on the western wall just below the 2nd ring.

U - This is on a ledge just before the 2nd ring.

S - This is on the eastern wall after the 2nd ring, about halfway up.

T - This is floating by the western wall just below the final ring.