TY  - BOOK
ED  - Congressional Research Service
TI  - Subterranean Operations 
T2  - Army Techniques Publication
PY  - 2019///
CY  - Washington
PB  - Department of the Army 
KW  - Operaciones militares
KW  - Estados Unidos
UR  - https://fas.org/irp/doddir/army/atp3-21-51.pdf
ER  -