All materials in the AHA Library are labeled by classmark, which is a combination of numbers and letters, often separated by a space (for example, 92.92 MUC, 473 BAR, etc.). The three letters after a number stand for the first three letters of the author's or the editor's last name, so if the letters after the number are missing, just add the first letters of the author's last name, and you'll find the book!
When you search for an item in iDiscover, it will display the item location (the library / libraries it is in) and its classmark.
When you click on the link showing availability ("Available at..."), you will access more information about the item.