Monograph:

( 1 )   B. Allison, G. Benkart, Y. Gao,  Lie algebras graded by the root system $BC_r$, $r\geq 2$,
          (158 pages)
         Memoirs of  the American Mathematical Society, Volume 158, Number 751(2002)

( 2 )   B. Allison, S. Azam, S. Berman, Y. Gao, A. Pianzola,    Extended Affine Lie Algebras and
         Their  Root Systems,  (122 pages)
         Memoirs of  the American Mathematical Society,  Volume 126, Number 603 (1997)

Journal:

 ( 1 )  Y. Gao,  S. Shang,  Universal coverings of Steinberg Lie algebras of small characteristic
          Journal  of Algebra  311(2007)  216--230

 ( 2 )  H. Chen,  Y. Gao,  BC_N-graded Lie algebras arising from fermionic representations
          Journal of  Algebra 308 (2007) 545--566

( 3 )   Y. Gao,  Z. Zeng,   Hermitian representations of the extended affine Lie
                     algebra $\tilde{gl_2(C_q)}$,

( 4 )   N. Bergeron, Y. Gao,  N. Hu,   Drinfel'd doubles and Lusztig symmetries of two-parameter
                     quantum groups,
          Journal of Algebra 301 (2006) 378--405

( 5 )   Y. Gao,  N. Jing,    $U_q(\hat{gl}_N)$-action on $\hat{gl}_N$-modules and quantum
                     toroidal algebras,
          Journal of Algebra  273  (2004) 320--343

( 6 )   S. Berman,  Y. Gao,  S. Tan,   A unified view of  some vertex operator constructions,
           Israel  Journal of Mathematics   134  (2003) 29--60

( 7 )   B. Allison,  Y. Gao,  The root system and the core of an extended affine Lie algebra,
           Selecta  Mathematica   7 (2001) 149--212

( 8 )   Y. Gao,  Representations of extended affine Lie algebras coordinatized by certain
           quantum tori,
          Compositio Mathematica  123 (2000) 1--25.

( 9 )   Y. Gao,   Vertex operators  arising from the homogeneous realization  for
           $\widehat{gl}_{{}_N}$,
          Communications in Mathematical Physics  211 (2000) 745--777.

( 10 )   B. Allison, G. Benkart,  Y. Gao,  Central extensions of Lie algebras graded by finite
           root systems,
           Mathematische Annalen  316 (2000) 499--527

( 11)   B. Allison, S. Berman, Y. Gao, A. Pianzola,   A characterization of affine Kac-Moody
            Lie algebras,
           Communications in Mathematical Physics 185 (1997) 671--688.

( 12 )  Y. Gao,   Involutive Lie Algebras Graded by Finite Root Systems and Compact  Forms
            of IM Algebras,
            Mathematische Zeitschrift  223 (1996) 651--672.

( 13 )   B. Allison,  Y. Gao,   Central Quotients and Coverings of  Steinberg Unitary Lie Algebras,
            Canadian Journal of  Mathematics  48 (1996)  449--482.

( 14 )   S. Berman, Y. Gao,  Y. Krylyuk,  Quantum Tori and the Structure of Elliptic Quasi-simple
            Lie Algebras,
            Journal of  Functional Analysis 135 (1996) 339 -- 389.

( 15 )   Y. Gao,  Steinberg Unitary Lie Algebras and Skew-dihedral Homology,
             Journal of  Algebra 179 (1996) 261--304.

( 16 )   S. Berman, Y. Gao, Y. Krylyuk,  E. Neher, The Alternative Torus  and the Structure of
            Elliptic Quasi-simple Lie Algebras of Type $A_2$,
            Transactions of  the American Mathematical Society  347 (1995) 4315--4363.