Suganuma Y., Okada M., Horie K., Kaiden H., Takehara M., Senda R., Kimura J., Kawamura K., Haneda Y., Kazaoka O. and Head M.J.,
2015, Age of Matuyama-Brunhes boundary constrained by U-Pb zircon dating of a widespread tephra. Geology, 43, 491-494.