Why am I getting this error: Incorrect syntax for definition of the table constraint

CREATE TABLE COMPUTER_ASSIGNMENT ( SerialNumber Int NOT NULL, EmployeeNumber Int NOT NULL, DateAssigned Date NOT NULL, DateReassigned Date NULL, CONSTRAINT SerialNumberPK PRIMARY KEY (SerialNumber, EmployeeNumber), REFERENCES COMPUTER (SerialNumber), CONSTRAINT SerialNumberFK FOREIGN KEY (SerialNumber, EmployeeNumber) REFERENCES EMPLOYEE (EmployeeNumber) );