From: On the solutions and conservation laws of the coupled Drinfeld-Sokolov-Satsuma-Hirota system
Ad
X 1
X 2
X 3
X 4
−3ε X 1 + X 4
−ε X 2 + X 4
4ε X 3 + X 4
3 e ε X 1
e ε X 2
e − 4 ε X 3