in Superman Supacomic (K. G. Murray, 1959 series) #64 (Circa December 1964)
in Superman Supacomic (K. G. Murray, 1959 series) #64 (Circa December 1964)
in Superboy (Williams Forlag, 1969 series) #2/1977 ([februar] 1977)Note in story indicates Mxyztptlk is pronounced "Mix-Yez-Pitel-Ik" (one of many pronounciations given over the years).