TY  - JOUR
AU  - Johannes Tambornino
TI  - Relational observables in gravity: a review
JO  - Symmetry, integrability and geometry: methods and applications
PY  - 2012
VL  - 8
UR  - http://geodesic.mathdoc.fr/item/SIGMA_2012_8_a16/
LA  - en
ID  - SIGMA_2012_8_a16
ER  -