“…However, one finds in the literature other plasma models, which then either lead to an equation like (23), but with more complicated coefficients, [12][13][14][15][16][17][18][19][20][21]24,25,30,32,33,36,[38][39][40][41][42]44,46,49,54 or to modifications of related evolution equations like the Burgers, 23,31,35 KdV-Burgers, 22,37,45,47,48 Gardner, [26][27][28][29]34,43,44,[50][51][52][53]55,56 or Schamel 23 equations. The standard forms of these equations have been well studied in the literature over many decades.…”