His research concentrates mainly on the editing and study of
sources for the history of the kingdom of Sicily in the Norman,
Swabia and Anjou periods and on themes of a political-institutional
nature relative to the history of the Papacy in the Low Middle
Ages.
The study of southern sources concentrated on the analysis of a
hybrid historiography genre, that of chronicles/cartularies,
particularly widespread in western Europe but limited in the
Italian peninsular to Benedictine centres in central-southern
Italy. A large part of his work is now devoted to the
reconstruction and study of a Registrum pheudatariorum of 1279,
once preserved in file 8 of the Anjou chancellery listing feudal
lords of the judiciary of Abruzzo, feudal asset values and lengths
of military service due. The study of such a document enables on
the one hand, a better understanding of the mechanisms regulating
military service of a feudal nature, and on the other to quantify
the effects of the introduction of French elements in the feudal
geography of a significantly wide region of the Kingdom in the
early Anjou period.
Work devoted to events of a political-institutional nature of the
papacy, instead, has resulted in a series of works on certain
aspects of Boniface VIII: instruments and aims of his propaganda,
affirmation of the papal universalism and relations with the German
court, aspects of the rule of territories under the apostolic seat,
difficulties in relations with the Roman nobility and in particular
with the families Colonna and Orsini.
In the same field of research, particular attention has been paid
to developments of the papacy of the 1300s (relations with outer
urban areas and the Studium of Bologna; war of the Otto Santi;
great west Europe schism) and the work of Giovanni da Legnano,
famous jurist of the Bologna Studium, brilliant politician and
respected pontiff legate, author of a treatise on the schism, il De
fletu Ecclesie (1378), which was widely-read in the latter years of
the 14th century. It was much discussed and bitterly contested by
cardinals from opposing allegiances, jurists from the University of
Paris and experts from various European courts.
