@ARTICLE{Kleer_Jerzy_Four_2016,
 author={Kleer, Jerzy},
 number={Nr 3 (47) Singularity},
 journal={ACADEMIA. The magazine of the Polish Academy of Sciences},
 pages={18-21},
 howpublished={online},
 year={2016},
 publisher={Polish Academy of Sciences},
 language={eng},
 abstract={They are linked to many issues in the economic, political, and social sciences. Their role in the changing world cannot be overestimated. Their significance, though unlikely to wane, will nonetheless be changing. What are “public goods” and what is their future?},
 type={Article},
 title={Four degrees of sovereignty},
 URL={http://journals.pan.pl/Content/112727/PDF/018-021%20kleer_ang.pdf},
 keywords={public goods, public goods and their future},
}