Waterman
The Waterman Method was created by Marc Waterman and Daan Krammer in 1981.
Several others published the same layer and last layer corners steps earlier in 1979.
Johnson, K.C. - The Magic Cube Puzzle - 1979
First layer
Solve last layer corners
Solve the last eight edges.
Truran, Trevor - Solving That Eastern Bloc(k) - 1979
First layer
Permute last layer corners
Orient last layer corners
Solve the last eight edges.
Cairns, Colin & Dave Griffiths - Teach Yourself Cube-Bashing - 1979
An extended version of Truran's publication
Angevine, James - Solution for the Magic Cube Puzzle - 1979
The same as Carins and Griffiths, which is the same as Truran
Ollerenshaw, Dame Kathleen - The Hungarian Magic Cube - 1980
First layer
Last layer corners
Middle layer edges
Last layer edges.
Bossert, Patrick - You Can Do The Cube - 1981
First layer corners
First layer edges
Bottom layer corners
Remaining edges.
I found much of this information in Notes on Rubik's 'Magic Cube' and other sources. I then reached out to Georges Helm. He checked the steps in the books that he owns and wrote them down for me.