Someone said about the cover of the book, "If the integral with respect to y is inside the integral with respect to x in an iterated integral, then dy should appear to the left of dx."  That's correct, but the integrals on the cover show an inside integral with respect to x, not y. Thus you treat y as a constant and integrate with respect to x, then evaluate y from 4 to 9 (in the cover's example). Finally evaluate the outer integral with respect to y. It's analogous to reversing the operation of partial diff of f with respect to x. The cover is correct.<br><br>Someone else said (in German) that this book is all about calculations, methods, and procedures, not proofs. That is true, it's not an analysis book.