From Dummit and Foote section 2.5.

11. Consider the group of order 16 with the following presentation: @D16 = (0, T | 08 = 12 = 1, Or = 103) (called the quasidihedral or semidihedral group of order 16). This group has three sub- groups of order 8: ( t, 02 ) ~ Do, (o ) ~ Zg and (o2, or ) = 2: and every proper subgroup is contained in one of these three subgroups. Fill in the missing subgroups in the lattice of all subgroups of the quasidihedral group on the following page, exhibiting each subgroup with at most two generators. (This is another example of a nonplanar lattice.)