  Purpose: We seek to explore the realm of literature about digital libraries.
We specifically seek to ascertain how interest in this subject has evolved, its
impact, the most productive journals and countries, the number of occurrences
of digital libraries, the relationships and dynamics of the main concepts
mentioned, and the dynamics of metadata formats.Methods: We extracted corpora
from the Google Scholar and Microsoft Academic Search bibliographic databases.
We analyzed the named entities and concepts contained within these corpora with
the help of text mining technologies, CorTexT in particular.Results: While the
number of publications on the subject of digital libraries is increasing, their
average number of citations is decreasing. China, the United States and India
are the most productive countries on the subject. Literature about conservation
and national libraries has gradually been replaced by literature about open
access, university libraries and the relationship with users. Internet Archive
is the most cited digital library in literature and continues to grow. Dublin
Core is the most talked about metadata format, however the subject of metadata
formats is declining in the corpus today.Conclusion: Digital libraries now seem
to be reaching the age of maturity.
