  There are different citation habits in the research fields that influence the
obsolescence of the research literature. We analyze the distinctive
obsolescence of research literature in disciplinary journals in eight
scientific subfields based on cited references distribution, as a synchronous
approach. We use both Negative Binomial (NB) and Poisson distributions to
capture this obsolescence. The corpus being examined is published in 2019 and
covers 22,559 papers citing 872,442 references. Moreover, three measures to
analyze the tail of the distribution are proposed: (i) cited reference survival
rate, (ii) cited reference mortality rate, and (iii) cited reference
percentile. These measures are interesting because the tail of the distribution
collects the behavior of the citations at the time when the document starts to
get obsolete in the sense that it is little cited (used). As main conclusion,
the differences observed in obsolescence are so important even between
disciplinary journals in the same subfield, that it would be necessary to use
some measure for the tail of the citation distribution, such as those proposed
in this paper, when analyzing in an appropriate way the long time impact of a
journal.
