transfer function - Consider an ideal low pass filter $H(\omega)$, and the input to this filter is the periodic square wave $x(t)$. Find the output $y(t)$ - Signal Processing Stack Exchange
Sampling and Reconstruction The impulse response of an continuous-time ideal low pass filter is the inverse continuous Fourier transform of its frequency. - ppt download
transfer function - Impulse response of IIR low-pass filter - Signal Processing Stack Exchange