3 Loop Quantum Gravity
Since many reviews of full loop quantum gravity [172, 195, 22
, 174, 161] as well as shorter accounts
[9, 10, 173, 190, 167, 198] are already available, we describe here only those properties which will be
essential later on. Nevertheless, this review is mostly self-contained; our notation is closest to that in [22]. A
recent bibliography can be found in [93].