This volume contains the edition -along with comments and interpretations- of selected Byzantine lead seals in the collection of Gert Boersema (the Netherlands), which are nearly exclusively unique specimens, dating from the 6th to the 14th century. The inscriptions offer new results and aspects for the Byzantine administrative history, prosopography, historical geography, and economic history, but furthermore concern the Byzantine church, monasteries, domains, and especially the Byzantine aristocracy. Short English abstracts contribute a kind of regestes, representing the value of the contents. The book is an attribution to basic research of Byzantine history.