The sampling theorem was implied by the work of Harry Nyquist in 1928, in which he showed that up to 2"B" independent pulse samples could be sent through a system of bandwidth "B"; but he did not explicitly consider the problem of sampling and reconstruction of continuous signals. About the same time, Karl Küpfmüller showed a similar result and discussed the sinc-function impulse response of a band-limiting filter, via its integral, the step-response sine integral; this bandlimiting and reconstruction filter that is so central to the sampling theorem is sometimes referred to as a "Küpfmüller filter" (but seldom so in English).