RAD Essentials 6th ed required for CORE and SKULL/SINUSISBN: 9780323661874 Merrill’s 15 ed Vol. 1 required for CHEST, EXTREMITIES, and SPINEHardcover ISBN: 9780323832809eBook: 9780323833288 Order at:Elsevier.comYou can also search the web by ISBN number for other options like Amazon.