Originally Posted by mrmikel
You need to open the book in Sigil. Then press control enter often enough so that the big long document is reduced to no file longer than 300k. Calibre uses 260k or so by default.
Many find it helpful to simply press control enter on the last period of a chapter. This will start a new file at the beginning of the following chapter. Doing by chapters can make it easier to edit, and load and display in lower powered devices.
Thanks! I will try to use Sigil here. But any other option? Just to have a back-up plan? )