并列题名：Applied partial differential equations:with fourier series and bounday value problems Applied partial differential equations:with fourier series and bounday value problems Applied partial differential equation with fourier series and boundary value problems elementary partial differential equations with boundary value problems elementary differential equations and boundary value problems 并列题名：Differential equations and boundary value problems Differential equations and boundary value problems elliptic differential equations and obstacle problems 并列题名：Fractional partial differential equations and their numerical solutions