Eigenvalues of the Dirac operator in the continuous spectrum

The functions $p(x)$ and $q(x)$ for which the Dirac operator
$$ \begin {gathered} Dy=\begin {pmatrix}0&1\\ -1&0\end{pmatrix} \frac {dy}{dx}+\begin {pmatrix}p(x)&q(x)\\ q(x)&-p(x)\end{pmatrix} y=\lambda y,\\ y=\begin {pmatrix}y_1\\ y_2\end{pmatrix} ,\qquad y_1(0)=0 \end {gathered} $$
has the counted number of eigenvalues located on the continuous spectrum are built.