What were the intentions of the artists who were making books? Germano Celant sets forth their concerns in the early period:

The years 1956-63 were however characterized by the dialectic between hot 'informel' and cool 'informel' when attention was transferred from the human and material elements to the relationship between man and his media. This change in emphasis coincided with the use of all existing media, not as means but as ends in themselves. (1)

As artists began to explore the use of new communication systems, the hegemony of painting and sculpture comes under attack, and with it the status of the privileged object. These new media initiated a profound questioning of the boundaries of the art work and art practice, and fostered a period in which, natural, biological, technological, linguistic, theoretical and philosophical systems were explored through a constellation of intermedial expressions.
Many of these communication systems were inherently duplicative, and this ability was seized upon in the attack on the discrete, and original art object. The concept of the 'multiple' promised an accessibility and 'democratization' of the object. It was only natural that bookmaking would receive the same scrutiny from artists exploring an expanded realm of media possibilities.
The artists' book fit naturally into the intermedial activities of this period and established itself as a site for a variety of practices: a primary site for theoretical discussions, documentation of conceptual projects, artist produced catalogues, in some cases the artwork itself, and for others the site of collaboration. The book the was the perfect container for these range of practices, as well as being one of the most expedient and economical means of disseminating new ideas within the ever increasing international community of like-minded artists. By 1968, "...art produced through the printed media, as opposed to being reproduced, increased rapidly..." (2)
From the vantage point of the '80s the eventual failure of artists' books to circumvent the commodification inherent in the established dealer and gallery system, even with the establishment of a parallel alternative distribution system, was evident. Artists' books did not end up lining the aisles in, "...supermarkets, drugstores and airports..." (3), they were still only to be found in specialized bookstores, many in limited editions, not all priced for the person off the street, and for the large part still addressing issues that would only be of concern to someone involved in the affairs of the art world.
On a more positive note what did occur was that artists realized the potential of self publishing their work in book form. Books offered the artists:

• Total control over the end product and the subsequent experimentation with typography, visual images, lay out and design.
  
• An accessible site for a range of concerns to be expressed and communicated, be they personal, social, or political.
  
• An important link in the transmission and exchange of new ideas across geographic and ideological distances, establishing networks of artists with similar interests and concerns (conceptual art, concrete poetry/visual poetry, Fluxus etc.).
  
• Direct communication to a potential audience not mediated by critics, art historians or other guardians of official culture.
  
• A number of affordable printing technologies within which projects could be realized depending upon the vagaries of personal funding, available grants, and other potential sponsors.

Bibliography
Crane, Michael. "Exhibitions and Publications." Correspondence Art. Michael Crane & Mary Stofflet, eds. San Francisco: Contemporary Arts Press, 1984.
Four page overview of mail art publications from early 1970s to late '70s. "Today's 'zines are reminiscent of earlier dada publications and may have sprung from similar concerns. The late 1960s and early 1970s, times of rapid widespread social change, can be seen as parallel to the turmoil which followed World War I. Responding to the latter was dada's cause: responding to the former was the cause of many contemporary artists. The periodical provided an excellent format and platform for both responses. 'Zines have become a tradition in mail art."

Banana, Anna. About VILE. Vancouver (Canada): Banana Productions, 1983.
This book includes an article by Banana titled "VILE History," which gives details about the seven issues that were published between 1974-80. "VILE was inspired by FILE Magazine's growing disdain for mail-art. It began at Speedprint, a small instant print shop in San Francisco where it became apparent to me that anyone could be a publisher."

Perneczky, Géza. A Háló. Budapest: A Héttorony Könyvkiadó, 1991.
The only substantial study of artists' periodicals between 1968-1988. This Hungarian book includes a brief English summary titled, "The magazine network: The trends of alternative art in the light of their periodicals 1968-1988." "The marginal artistic trends that have sprung up in the past decades from the various subcultures and from the alternative endeavors that broke with the officially sanctioned art (for example mail art or the popular branches of visual poetry or graphic art) have rediscovered the genre of art periodicals for the connoisseur. The publishers of these periodicals adopted the time-honored editorial practice of non-profit papers and coupled it with non-professional design and with a worldwide register of addresses to launch an exchange network. Moreover, these new-born "samizdats" took advantage of the inexpensive techniques of instant printing and photocopying. As a result, the early seventies witnessed the emergence of an international network of hundreds of such alternative titles. The present volume has set itself the task to collect and evaluate this Magazine Network."