Henk W. Smit K. Verton Cornelis A. Grimbergen A Low-Cost Multichannel Preamplifier for Physiological Signals. 307-310 1987 34 IEEE Trans. Biomed. Eng. 4 https://doi.org/10.1109/TBME.1987.326092 https://www.wikidata.org/entity/Q68843207 db/journals/tbe/tbe34.html#SmitVG87 streams/journals/tbe