The text is the same that we have used for several years. There
are a couple of different versions of the 9th edition (see below).
Elementary Differential Equations and Boundary Value Problems,
by William Boyce and Richard DiPrima (9th Edition)
TEXT NOTE: This is NOT the current version,
which is the 10th edition. There are a couple of different versions
of the text; here are the links to Amazon.com for the information: