# metadata.dc.description.abstract[].value
The aim of trepidation models was to account for two phenomena that puzzled medieval astronomers: the secular decrease of the obliquity of the ecliptic, and the apparent changes in the velocity of precession over the years.

# metadata.dc.relation.ispartof[].value
Suhayl. Journal for the History of the Exact and Natural Sciences in Islam, 2001, vol. 2, p. 291-408

# metadata.dc.source[].value
Articles publicats en revistes (Filologia Clàssica, Romànica i Semítica)