Dirac--Sobolev Spaces and Sobolev Spaces

The aim of this work is to study the first order Dirac-Sobolev spaces in $L^p$ norm on an open subset of ${\mathbb R}^3$ to clarify its relationship with the corresponding Sobolev spaces. It is shown that for $1< p <\infty$, they coincide, while for $p=1$, the latter spaces are proper subspaces of the former.