Weber J N, Keith M L
Science. 1962 Nov 23;138(3543):900-2. doi: 10.1126/science.138.3543.900.
The C(13):C(12) ratios of the carbonate comprising "normal," "faunal," and "mixed" coal balls are consistent with the hypothesis that calcareous coal balls contain varying proportions of two kinds of carbonate: (i) precipitated carbonate formed in the coal swamp and characteristically deficient in C(13), and (ii) extraneous detrital material, mainly fossil fragments relatively enriched in C(13).
构成“正常”、“动物群”和“混合”煤球的碳酸盐的C(13):C(12)比值与以下假设一致：钙质煤球包含两种比例不同的碳酸盐：(i) 在煤沼泽中沉淀形成的碳酸盐，其特征是C(13)含量不足；(ii) 外来碎屑物质，主要是相对富含C(13)的化石碎片。
