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  1. Fossils of Ontario.
    By: Bolton, Thomas Elwood, - Copeland, M. J. - Ludvigsen, Rolf. - Wagner, Frances J. E., - Royal Ontario Museum.
    Publication info: Toronto :Royal Ontario Museum,1979-1985.
    Contributed by: Royal Ontario Museum (archive.org)
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  2. The Ordovician trilobite Pseudogygites Kobayashi in eastern and Arctic North America /
    By: Ludvigsen, Rolf. - Royal Ontario Museum.
    Publication info: Toronto :Royal Ontario Museum,1979.
    Contributed by: ROM - University of Toronto (archive.org)
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  3. Silurian trilobites from the northern Yukon Territory /
    By: Ludvigsen, Rolf. - Tripp, Ronald P. - Royal Ontario Museum.
    Publication info: Toronto :Royal Ontario Museum,1990. c1989.
    Contributed by: Royal Ontario Museum (archive.org)
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  4. The trilobites Bathyurus and Eomonorachus from the Middle Ordovician of Oklahoma and their biofacies significance /
    By: Ludvigsen, Rolf. - Royal Ontario Museum.
    Publication info: Toronto :Royal Ontario Museum,1978.
    Contributed by: ROM - University of Toronto (archive.org)
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  5. Upper Cambrian and Lower Ordovician trilobite biostratigraphy of the Rabbitkettle Formation, Western District of Mackenzie /
    By: Ludvigsen, Rolf. - Royal Ontario Museum.
    Publication info: Toronto :Royal Ontario Museum,1982.
    Contributed by: ROM - University of Toronto (archive.org)
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  6. Upper Cambrian to Lower Ordovician conodont biostratigraphy and biofacies, Rabbitkettle Formation, District of Mackenzie /
    By: Landing, Ed. - Ludvigsen, Rolf. - Von Bitter, Peter H. - Royal Ontario Museum.
    Publication info: Toronto :Royal Ontario Museum,1980.
    Contributed by: ROM - University of Toronto (archive.org)
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