On recovering Dirac operators with two delays

We study the inverse spectral problems of recovering Dirac-type functional-differential operator with two constant delays $a_1$ and $a_2$ not less than one-third of the interval. It has been proved that the operator can be recovered uniquely from four spectra under the condition $2a_1+\frac{a_2}{2}\geq \pi$, while it is not possible otherwise.