<a href="//commons.wikimedia.org/w/index.php?title=Chemical_structure&amp;action=edit&amp;redlink=1" class="new" title="Chemical structure (page does not exist)">Chemical structures</a> of major endogenous <a href="//commons.wikimedia.org/w/index.php?title=Estrogen&amp;action=edit&amp;redlink=1" class="new" title="Estrogen (page does not exist)">estrogens</a>, including <a href="//commons.wikimedia.org/w/index.php?title=Estrone&amp;action=edit&amp;redlink=1" class="new" title="Estrone (page does not exist)">estrone</a> (E1), <a href="//commons.wikimedia.org/w/index.php?title=Estradiol&amp;action=edit&amp;redlink=1" class="new" title="Estradiol (page does not exist)">estradiol</a> (E2), <a href="//commons.wikimedia.org/w/index.php?title=Estriol&amp;action=edit&amp;redlink=1" class="new" title="Estriol (page does not exist)">estriol</a> (E3), and <a href="//commons.wikimedia.org/w/index.php?title=Estetrol&amp;action=edit&amp;redlink=1" class="new" title="Estetrol (page does not exist)">estetrol</a> (E4).
Coelingh Bennink, H. J. T., Holinka, C. F., &amp; Diczfalusy, E.
Coelingh Bennink, H. J. T., Holinka, C. F., &amp; Diczfalusy, E. (2008). Estetrol review: profile and potential clinical applications. Climacteric, 11(sup1), 47-58. <a rel="nofollow" class="external free" href="https://www.tandfonline.com/doi/abs/10.1080/13697130802073425">https://www.tandfonline.com/doi/abs/10.1080/13697130802073425</a>