From An Introduction to the Theory of Traveling Waves, by Erwin Weber:

Notice that there is a star in front of the numbers for the above equations. Equations thus identified in the remainder of the text are to be forgotten. The equations are unimportant and any student who commits them to memory deserves to spend his entire electrical engineering career grabbing the hot end of a soldering iron. These equations may be useful in impressing your friends – those that don’t know any better – but other than this, they serve no useful purpose.