Notes on highest weight modules of the elliptic algebra ${\cal   A}_{q,p}\left(\widehat{sl}_2\right)$
  We discuss a construction of highest weight modules for the recently defined elliptic algebra ${\cal A}_{q,p}(\widehat{sl}_2)$, and make several conjectures concerning them. The modules are generated by the action of the components of the operator $L$ on the highest weight vectors. We introduce the vertex operators $\Phi$ and $\Psi^*$ through their commutation relations with the $L$-operator. We present ordering rules for the $L$- and $\Phi$-operators and find an upper bound for the number of linearly independent vectors generated by them, which agrees with the known characters of $\widehat{sl}_2$-modules. 
O. Foda, K. Iohara, M. Jimbo, R. Kedem, T. Miwa and H. Yan