TY  - RPRT
TI  - Letter Circular 307: specifications for haemacytometer chambers (superseding Letter Circular 240)
PY  - 1931
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 307
DO  - 10.6028/NBS.LCIRC.307
ER  -