Some applications of eta-quotients
  We show that every modular form on $\Gamma_0(2^n)$ ($n\geq2$) can be expressed as a sum of eta-quotients. Furthermore, we construct a primitive generator of the ring class field of the order of conductor $4N$ ($N\geq1$) in an imaginary quadratic field in view of the special value of certain eta-quotient. 
Ick Sun Eum, Ja Kyung Koo and Dong Hwa Shin
math.NT