Rickard, L. V. (1962). Late Cayugan (upper Silurian) and Helderbergian (lower Devonian) stratrigraphy in New York. University of the State of New York, State Education Dept..
Chicago-viite (17. p.)Rickard, Lawrence V. Late Cayugan (upper Silurian) and Helderbergian (lower Devonian) Stratrigraphy in New York. Albany: University of the State of New York, State Education Dept., 1962.
MLA-viite (8. p.)Rickard, Lawrence V. Late Cayugan (upper Silurian) and Helderbergian (lower Devonian) Stratrigraphy in New York. University of the State of New York, State Education Dept., 1962.
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