  New exact solutions to the KdV2 equation (known also as the extended KdV
equation) are constructed. The KdV2 equation is a second order approximation of
the set of Boussinesq's equations for shallow water waves which in first order
approximation yields KdV. The exact solutions
~$\frac{A}{2}\left(\dn^2[B(x-vt),m]\pm \sqrt{m}\,\cn [B(x-vt),m]\dn
[B(x-vt),m]\right)+D$~ in the form of periodic functions found in the paper
complement other forms of exact solutions to KdV2 obtained earlier, i.e., the
solitonic ones and periodic ones given by a single $\cn^2$ or $\dn^2$ Jacobi
elliptic functions.
