Nonlocal symmetries and similarity reductions for Korteweg–de Vries–negative-order Korteweg–de Vries equation
Hu Heng-Chun †, Liu Fei-Yan
       

The solitary wave solution u expressed by Eq. (41) of the KdV–nKdV equation with Eq. (40) and the constants selection k = b = c3 = 1, c2 = 3, Δ = 7.