Cita APA (7a ed.)
Ullmann, W. Principles of Government and Politics in the Middle Ages. Methuen ; Barnes and Noble.
Cita estilo Chicago (17a ed.)
Ullmann, Walter. Principles of Government and Politics in the Middle Ages. Londres, Inglaterra : Nueva York, EUA: Methuen ; Barnes and Noble.
Cita MLA (9a ed.)
Ullmann, Walter. Principles of Government and Politics in the Middle Ages. Methuen ; Barnes and Noble.
警告：这些引文格式不一定是100％准确.