I am working on classifying all groups of order less than or equal to 100. For most orders, this is fairly straightforward, since we can just utilize Cauchy's Theorem/Sylow's Theorems to show that the group can be expressed as a semi-direct product and then find the desired automorphism. However, for p-groups the same procedure doesn't really work. In particular, I need to tackle the following two cases: Classify all groups of order p4 where p is a prime. Classify all groups of order 2k where 5 ≤ k ≤ 6. If anyone has any sources on these problems or knows how to tackle one them, the help is appreciated. Thanks.