E. D. Clayton, ANOMALIES OF NUCLEAR CRITICALITY, REVISION 6 [Архівовано 24 вересня 2015 у Wayback Machine.] // Pacific Northwest Laboratory, February 2010. page 79. «N. THE CRITICALITY OF 239Pu-240Pu METAL MIXTURES»: «The critical mass for 239Pu metal is given as 5.2 and 10 kg for water-reflected and bare spheres, respectively.»(англ.)
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E. D. Clayton, ANOMALIES OF NUCLEAR CRITICALITY, REVISION 6 [Архівовано 24 вересня 2015 у Wayback Machine.] // Pacific Northwest Laboratory, February 2010. page 79. «N. THE CRITICALITY OF 239Pu-240Pu METAL MIXTURES»: «The critical mass for 239Pu metal is given as 5.2 and 10 kg for water-reflected and bare spheres, respectively.»(англ.)