Palais et al. 1987, p. 804. Palais, J. M.; Kyle, P. R.; Mosley-Thompson, E.; Thomas, E. (August 1987). "Correlation of a 3,200 year old tephra in ice cores from Vostok and South Pole Stations, Antarctica". Geophysical Research Letters. 14 (8): 804–807. Bibcode:1987GeoRL..14..804P. doi:10.1029/GL014i008p00804.
Palais et al. 1987, p. 804. Palais, J. M.; Kyle, P. R.; Mosley-Thompson, E.; Thomas, E. (August 1987). "Correlation of a 3,200 year old tephra in ice cores from Vostok and South Pole Stations, Antarctica". Geophysical Research Letters. 14 (8): 804–807. Bibcode:1987GeoRL..14..804P. doi:10.1029/GL014i008p00804.