@article{Zopf_1974, title={Variations in support burdens as measured by the dependency ratio}, volume={19}, url={https://ejournals.epublishing.ekt.gr/index.php/ekke/article/view/6934}, DOI={10.12681/grsr.295}, abstractNote={[Δε διατίθεται περίληψη / no abstract available]}, journal={The Greek Review of Social Research}, author={Zopf, Paul E.}, year={1974}, month={Jan.}, pages={29–43} }