We show that there are only finitely many nonconstant reflective automorphic forms $\Psi$ on even lattices of squarefree level splitting two hyperbolic planes and give a complete classification in the case where the zeros of $\Psi$ are simple and $\Psi$ has singular weight.
Complete classification of 2-ramified power series
The Eisenstein ideal with squarefree level
Higher congruences between newforms and Eisenstein series of squarefree level
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