  Multidisciplinary cooperation is now common in research since social issues
inevitably involve multiple disciplines. In research articles, reference
information, especially citation content, is an important representation of
communication among different disciplines. Analyzing the distribution
characteristics of references from different disciplines in research articles
is basic to detecting the sources of referred information and identifying
contributions of different disciplines. This work takes articles in PLoS as the
data and characterizes the references from different disciplines based on
Citation Content Analysis (CCA). First, we download 210,334 full-text articles
from PLoS and collect the information of the in-text citations. Then, we
identify the discipline of each reference in these academic articles. To
characterize the distribution of these references, we analyze three
characteristics, namely, the number of citations, the average cited intensity
and the average citation length. Finally, we conclude that the distributions of
references from different disciplines are significantly different. Although
most references come from Natural Science, Humanities and Social Sciences play
important roles in the Introduction and Background sections of the articles.
Basic disciplines, such as Mathematics, mainly provide research methods in the
articles in PLoS. Citations mentioned in the Results and Discussion sections of
articles are mainly in-discipline citations, such as citations from Nursing and
Medicine in PLoS.
