  We provide the representation of quasi-periodic solutions of periodic Dirac
equations in terms of the spectral parameter power series (SPPS) recently
introduced by V.V. Kravchenko (2008,2009). We also give the SPPS form of the
Dirac Hill discriminant under the Darboux nodeless transformation using the
SPPS form of the discriminant and apply the results to one of Razavy's
quasi-exactly solvable periodic potentials
