Additional Equations Derived from the Ryder Postulates in the (1/2,0)+(0,1/2) Representation of the Lorentz Group

Developing recently proposed constructions for the description of particles in the $(1/2,0)\oplus (0,1/2)$ representation space, we derive the second-order equations. The similar ones were proposed in the sixties and the seventies in order to understand the nature of various mass and spin states in the representations of the $O(4,2)$ group. We give some additional insights into this problem. The used procedure can be generalized for {\it arbitrary} number of lepton families.