Book Review: Optional Instruments of the European Union, by William Bull. (Antwerp: Intersentia, 2016) - Common Market Law Review View Book Review: Optional Instruments of the European Union, by William Bull. (Antwerp: Intersentia, 2016) by - Common Market Law Review Book Review: Optional Instruments of the European Union, by William Bull. (Antwerp: Intersentia, 2016) 54 4 Common Market Law Review