This website, the supplement to Elements of Slow-Neutron Scattering (Cambridge University Press 2015), by John M. Carpenter and Chun-Keung Loong, offers material that elaborates on and extends the information in the book. Keywords leading to these items appear in square brackets in Elements that refer to Carpenter and Loong 2015, this site (for example, CL2015 [Lethargy]). In addition, the authors supply information that may not be easily accessible elsewhere. Browsing this supplement independently of the book may reveal further useful knowledge.