The relation of concretions to coal seams

Pyritic cone-in-cone concretions

Bertram G. Woodland

The nature and origin of cone-in-cone structure

Bertram G. Woodland

Origin and age of Fe-Mn-P concretions and nodules in an Oregon wetland

Scott R. Stewart

An organic origin for the carbonate concretions of the Ohio Shale

R. E. Criss

Concretions from the Champlain clays of the Connecticut Valley

J. M. Arms Sheldon

Calcareous concretions of the Omarolluk Formation, Belcher Islands, Northwest Territories

Kieselsäureanreicherungen in den oberjurassischen Sedimenten der Schwäbischen Alb

Martin Beurer

The pipy concretions of the Arikaree

C. Bertrand Schultz

Origin of marine oöids and grapestones

Frank H. Fabricius