Sequential palynological changes across the composite Cretaceous - Tertiary (K/T) Boundary claystone and contiguous strata, western Canada and Montana, U.S.A.
Reference:
Sweet,A.R. et al. (1999)
Sequential palynological changes across the composite Cretaceous - Tertiary (K/T) Boundary claystone and contiguous strata, western Canada and Montana, U.S.A. Canadian Journal of Earth Sciences
Vol. 36 # 5 P. 743- 768