TY  - RPRT
TI  - A simplified method for determining the angle between two spatial vectors.
AU  - R A HELM
AU  - N O FOWLER
PY  - 1953
DO  - 10.1016/0002-8703(53)90131-8
UR  - https://pubmed.ncbi.nlm.nih.gov/13050595/
ID  - 13050595
ER  -