A valuable resource for finding relevant literature is the
``Bibliography of Publications Related to Classical and
Quantum Gravity in terms of Connection and Loop
Variables'', organized chronologically. The original version was compiled
by Peter Hübner in 1989. It has subsequently been updated by
Gabriella Gonzales, Bernd Brügmann, Monica Pierri and Troy
Shiling. Presently, it is being kept updated by Christopher
Beetle and Alejandro Corichi. The latest version can be found
on the net in .
This ``living review'' may serve as an up to date
introduction to quantum gravity in the loop formalism. More
detailed (but less up to date) presentations are listed below.
 may serve as a valuable basic introductory course on
Ashtekar variables, particularly for relativists and
mathematicians. The part of the book on the loop
representation is essentially an authorized reprint of parts
the original Rovelli Smolin article
. For this quantum part, I recommend looking at the article,
rather than the book, because the article is more
A simpler and more straightforward introduction to the
Ashtekar variables and basic loop ideas can be found in the
Rovelli's review paper
. This is more oriented to a reader with a physics
A recent general introduction to the new variables which
includes several of the recent mathematical developments in
the quantum theory is given by
Ashtekar's Les Houches 1992 lectures
A particularly interesting collection of papers can be
the volume  edited by John Baez
. The other
book by Baez, and Muniain
, is a simple and pleasant introduction to several ideas and
techniques in the field.
The last and up to date book on the loop representation
the book by Gambini and Pullin
, especially good in lattice techniques and in the variant
of loop quantum gravity called the ``extended loop
78] (which is nowadays a bit out of fashion, but remains an
intriguing alternative to ``orthodox'' loop quantum
The two standard references for a complete presentation
of the basics of the theory are:
DePietri and Rovelli  for the algebraic formulation
Ashtekar, Lewandowski, Marolf, Mourao and Thiemann ()  for the differential formulation
Besides the many conferences on gravity, the loop gravity
community has met twice in Warsaw, in the
``Workshop on Canonical and Quantum Gravity''
. Hopefully, this will become a recurrent meeting. This may be
the right place to go for learning what is going on in the
field. For an informal account of the last of these meetings
(August 1997), see .
Some of the main institutions where loop quantum gravity is
``Center for Gravity and Geometry''
at Penn State University, USA. I recommend their invaluable
web page , maintained by Jorge Pullin, for finding anything you need from the web.