by Bartholdy, J., Kvale, E.P.
Published in Marine geology (20.12.2006)

by Sonett, C. P., Kvale, E. P., Zakharian, A., Chan, Marjorie A., Demko, T. M.
Published in Science (American Association for the Advancement of Science) (05.07.1996)

by Mastalerz, M., Stankiewicz, A.B., Salmon, G., Kvale, E.P., Millard, C.L.
Published in International journal of coal geology (01.09.1997)