There is a RootsSearch tool on the right side of your ancestors profiles. It will give you several places to look for sources. You sign in with the same email and password that you use to sign into WikiTree.
I just found several records for your great-grandfather Hugh Powell. I could not add them for you because of your privacy settings on the profile.
FamilySearch has a census with his parents, WWI record, Social Security Index (has his birth and death dates) and a Death record that I found so far. You can find a lot of records on FamilySearch. If you use RootsSearch to go to FamilySearch it will fill in the data from the profile for you.