sentences:  Sagitov (1969) based on the measurement of "G" by Heyl and Chrzanowski (1942) cited a value of (relative uncertainty ).Accuracy has improved only slightly since then.Most modern measurements are repetitions of the Cavendish experiment, with results (within standard uncertainty) ranging between 6.672 and 6.676 ×10−11  m3 kg−1 s−2 (relative uncertainty 3×10−4) in results reported since the 1980s, although the 2014 NIST recommended value is close to 6.674×10−11  m3 kg−1 s−2 with a relative uncertainty below 10−4.