Robert's writings can be divided into those printed and those in manuscript.

For the earlier projects Robert produced printed booklets to accompany the exhibitions, providing commentary on the philosophical themes contained (I think there's a complete list of them on this site somewhere); the 'middle period' projects were accompanied by pamphlets giving lists of the paintings and some choice quotes from other authors. The very latest projects also merited longer booklets (I'm thinking of Blind Tobit). Robert also published the Notes on the Barbican Mural to accompany, umm, the Barbican Mural.

Robert also occasionally wrote short articles for the local rag. I have copies of several of these though doubt there's a complete bibliography available at present.

The manuscript writings are considerably more extensive than those published and for the most part reside at the Studio. Robert kept a journal that he entitled Diary Notes throughout the latter 2/3 or so of his life, commencing in 1966 and running (often with lacunae) until about 2000. These exist as annual volumes, often hand-bound.

Everyone is aware of the Project Notebooks, and these were produced at the same time as the relevant project, testing out ideas and sketches for the project in question. The Notebooks were viewed by Robert as part of the project, though their contents are nowhere near so well known. Some paintings merited notebooks of their own, such as the Deathbed painting. To date only the Mary Notebook has been published (partially), though the texts of some of the early books were published in pamphlet form (such as Death and the Maiden).

The Aesthetic Notebooks chronicled various of Robert's relationships: many were done by him, many were done by his companions in arms though these often contained notes by Robert. There are supposed to be several hundred of these, though the actual figure is probably about a tenth thereof. There are also a quantity of loose, single sheet aesthetic notes on various themes personal to Robert. Some of these have been auctioned already.

There are various letters and notes by Robert, though he was not much of a letter writer. I'm not sure how many there may be of these. Robert was not in the habit of annotating his books but I know that some books of especial interest were noted in. These notes should also be included.