Sanderson, W.C. <https://pure.iiasa.ac.at/view/iiasa/265.html> & Scherbov, S. <https://pure.iiasa.ac.at/view/iiasa/270.html> ORCID: https://orcid.org/0000-0002-0881-1073 <https://orcid.org/0000-0002-0881-1073>  (2007).  A new perspective on population aging.   Demographic Research 16 (2) 27-58. 10.4054/DemRes.2007.16.2 <https://doi.org/10.4054/DemRes.2007.16.2>.