1. Variation in concentration of radiocarbon with time and location on earth;de Vries;Proc. Koninkl. Ned. Akad. Wetenschap.,1958
2. Variations in the atmospheric radiocarbon concentration over the past 1300 years;Willis;Am. J. Sci. Radiocarbon Suppl.,1960
3. Bristlecone-pine calibration of the radiocarbon time-scale 5200 B.C.;Suess,1970
4. Arizona radiocarbon dates for dendrochronologically dated samples;Damon,1970
5. MASCA radiocarbon dates for sequoia and bristlecone-pine samples;Ralph,1970