ARTICLE PDF ADDITIONAL INFORMATION The online version of the original article can be found at 10.1038/217136a0 RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS

ARTICLE Erratum. _Nature_ 217, 1084 (1968). https://doi.org/10.1038/2171084d0 Download citation * Issue Date: 16 March 1968 * DOI: https://doi.org/10.1038/2171084d0 SHARE THIS ARTICLE Anyone

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