Valery A.Yumaguzhin,

Contact classification of 3-order linear ordinary differential equations. 


It is well known that any 3-order linear ordinary differential equation 
can be transformed to the form 
$$
  y^{(3)}=a_1(x)y^{(1)}+a_0(x)y
$$
by a point transformation of variables. 

We give the classification of 3-order linear ordinary differential 
equations of this form in a neighborhood of a regular point up to a contact 
transformation.