On the Fine Structure of Quadratical Quasigroups

We prove that quadratical quasigroups form a variety Q of right and left simple groupoids. New examples of quadratical quasigroups of orders 25 and 29 are given. The fine structure of quadratical quasigroups and inter-relationships between their properties are explored. The spectrum of Q is proved to be contained in the set of integers equal to 1 plus a multiple of 4.