RH
Meaning of RH in English
I. ˌär-ˈāch adjective
Date: 1940
: of, relating to, or being an Rh factor
Rh antigens
Rh sensitization in pregnancy
II. symbol
rhodium
Merriam-Webster's Collegiate English vocabulary.
Энциклопедический словарь английского языка Merriam Webster.
2003