circulatory system of <i>Viviparus contectus</i>
Karl Hescheler (1868-1940), Arnold Lang (1855-1914) (ed.)
Hescheler K. (1900). Mollusca. In: Lang A. (ed.). <i>Lehrbuch der vergleichenden Anatomie der wirbellosen Thiere</i>. Jena, 510 pp., <a rel="nofollow" class="external text" href="https://archive.org/stream/lehrbuchdervergl01lang#page/323/mode/1up">page 323</a>, figure 294.