The ISBN of War of the Twins is 0-7869-1805-5.
The ISBN of Time of the Twins is 0-7869-1804-7.
The ISBN for "Test of the Twins" by Margaret Weis and Tracy Hickman is 978-0-88038-352-7.
The ISBN of The Ghost War is 9780399154539.
The ISBN of Highways to a War is 0855616423.
The ISBN of Hitler's War is 0670374121.
The ISBN of Our Worlds at War is 1401211291.
The ISBN of Clara's War is 9780061728600.
The ISBN of The Cool War is 0394293835.
The ISBN of Zen at War is 074253927X.
The ISBN of Forge of War is 1934506362.
The ISBN of Fitzpatrick's War is 0756401968.
The ISBN of The Gods of War is 0007164769.