Stress Location for TET4 and TET10 elements


Hello everyone!

Can anyone explain me how Nastran calculates stress in the linear tetrahedral element? Is the stress calculate in one integration point, which coresponds to centorid of element? And how to view this value in Femap with postprocessing toolbox? 
On the other hand, i want to calculate stress value at node of linear tetrahedral element, so which is correct way for calculating and presenting results?

And similary, for tet10 elements does Nastran calculate stress in three integration points, and then in node presents value of nearest integration point?

Thanks in advance!