Recently, an interesting article on the development of the field of digital libraries by two key persons of our community was published on LIBER Quarterly. LQ is an open access journal and you may find the article at:
Thanos, C. & Casarosa, V., (2017). The key role of the DELOS Network of Excellence in establishing Digital Libraries as a research field in Europe. LIBER Quarterly. 26(4), pp.296–307. DOI: http://doi.org/10.18352/lq.10165