Star Wars: Shadows of the Empire Easter Egg - THX-1138 Reference

This is an excerpt from page 336 of the book, (this is my copy, if yours is different, it's among the first few pages of chapter 37) fourth paragraph. It's the part where Luke and friends attack the six gaurds outside the sewage plant while trying to rescue Leia.

"From the comlink came a tinny voice: "Thix? What is going on down there? Thix? Come in Sector one-one-three-eight, come in-"

The sector number, 1138, is in reference to George Lucas' first movie, THX-1138. The name of the gaurd, Thix, may also be a reference.
Thix - i = Thx)