The call number of a book is like the address on the shelf. If you need help locating books ask at the Service Desk.
The call number means the following:
248.4 = class or subject number
P665D3 = author information + title information (first letter of author's last name and numbers for following letters + first letter of title and a number to make it unique if necessary)
Reference, Media and 0-249 call numbers are located on the upper level. Curriculum Materials Center (CMC) as well as 250-999 call numbers can be found on the lower level.