Many of these are “niche” books that simply wouldn’t work as ebooks. Nor would they have a wide enough market to justify the larger publishing houses printing them on paper. Yet they are valuable volumes.
Many important keys to improving your writing can be summed up in two words: pay attention. Absorb everything and use it to your advantage. It doesn’t have to be torture, but can really be quite productive.
You must have heard at least one of those very interesting statements issued by a police officer or other official public spokesperson. You know, the ones where they use “important” words instead of ordinary English?