  Academic publications have been evaluated in terms of their impact on
research communities based on many metrics, such as the number of citations. On
the other hand, the impact of academic publications on industry has been rarely
studied. This paper investigates how academic publications contribute to
software development by analyzing publication citations in source code comments
in open source software repositories. We propose an automated approach for
detecting academic publications based on Named Entity Recognition, and achieve
0.90 in $F_1$ as detection accuracy. We conduct a large-scale study of
publication citations with 319,438,977 comments collected from 25,925 active
repositories written in seven programming languages. Our findings indicate that
academic publications can be knowledge sources for software development. These
referenced publications are particularly from journals. In terms of knowledge
transfer, algorithm is the most prevalent type of knowledge transferred from
the publications, with proposed formulas or equations typically implemented in
methods or functions in source code files. In a closer look at GitHub
repositories referencing academic publications, we find that science-related
repositories are the most frequent among GitHub repositories with publication
citations, and that the vast majority of these publications are referenced by
repository owners who are different from the publication authors. We also find
that referencing older publications can lead to potential issues related to
obsolete knowledge.
