“…The corresponding data on boron isotope variations partly contradict each other: Parwel et al (1956), McMullen et al (1961), Finley et al (1962), Shima (1963), Agyei and McMullen (1968), and Schwarcz et al (1969). These contradicting results might be due mainly to erroneous measurements, because boron is difficult to handle in mass-spectrometric measurements.…”