Back in 2005, dual-line indoor kite flying expert: Harold Slit, wrote a short book all about flying (dual-line) kites indoors: "Indoor = No Wind = More Fun", but you probably haven't read it as it was published in Dutch.
Harold always meant to release an English version. And in January 2009, John Farrell (USA) did a mainly computer translation of the text, copies of which have been circulating around the English speaking community.
Anyway, thanks to the inspiration of the recent Southampton indoor session, and my late mother's Dutch heritage, Harold and I have taken his partly completed translation, John's file, some of my translations, and some new and some revised material from Harold, and created a full English version (complete with all the original pictures).
You can download a pdf of it from: http://www.flyingkites.nl - Please press the "Indoor" button.
Hope you enjoy it.