Fluxes of thin slab cells calculated by discrete SN method, DSN(N = 2, 4, 8, 16), single-spherical harmonics, PN(N = 1, 3, ⋯, 11, 13), and double-spherical harmonics, DPN(N = 1, 2, 3, 4, 5), are compared. The anisotropic flux component occurs predominantly in the region about µ = 0. The spatially dependent part of the spatial flux is largely determined by a few nearest-neighbor source regions. The anisotropic flux component originates largely from the isotropic effective sources arising from the nonspatially dependent part of the spatial flux. Two quadrature forms, for use in discrete ordinate methods of solutions for thin cells, are described which emphasize the small