Subnormal Solutions of higher Order Linear Differential Equations with Periodic Coefficients

The representations of subnormal solutions for the higher order linear differential equation $$f^{(n)}+\sum\limits_{j=1}^{n}[P_{n-j} (\mathrm{e}^z)+ Q_{n-j} (\mathrm{e}^{-z})] f^{(n-j)} = R_1(\mathrm{e}^z) + R_2 (\mathrm{e}^{-z})$$ are obtained, where $n\geq 2$, $P_j (z), Q_j (z)(j=0,1,2,\cdots, n-1)$, $R_1(z)$ and $R_2(z)$ are polynomials in $z$ such that $P_j (z), Q_j (z)$ $(j=0,1,2,\cdots, n-1)$ are not all constants, and $\deg P_{j}\deg P_0$ ,$(j=1,2,\cdots, n-1)$.