帮朋友求助几篇老文献，非常感谢各位相助！
1.Measurement of lead isotopes by differential atomic absorption
Willis H. Brimhall
Anal. Chem., 1969, 41 (10), pp 1349–1351
    http://pubs.acs.org/doi/abs/10.1021/ac60279a036

2.Bestimmung des Isotopenmischungsverhältnisses von Bleiproben mit der Atomabsorptionsmethode
H. Klrchhof
Spectrochimica Acta Part B: Atomic Spectroscopy
Volume 24, Issue 4, April 1969, Pages 235-241
  http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6THN-44XWWK3-3F&_user=1915929&_coverDate=04%2F30%2F1969&_rdoc=5&_fmt=high&_orig=browse&_srch=doc-info(%23toc%235287%231969%23999759995%23281954%23FLP%23display%23Volume)&_cdi=5287&_sort=d&_docanchor=&_ct=5&_acct=C000055340&_version=1&_urlVersion=0&_userid=1915929&md5=89ea8d564c05abd033a80977fa0c5b38

3.The use of a discharge tube as an absorption source for the determination of lithium-6 and lithium-7 isotopes by atomic absorption spectrophotometry
Joseph A. Goleb and Yu Yokoyama
Analytica Chimica Acta
Volume 30, 1964, Pages 213-222
  http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TF4-44YYW03-50&_user=1915929&_coverDate=12%2F31%2F1964&_rdoc=36&_fmt=high&_orig=browse&_srch=doc-info(%23toc%235216%231964%23999699999%23282933%23FLP%23display%23Volume)&_cdi=5216&_sort=d&_docanchor=&_ct=100&_acct=C000055340&_version=1&_urlVersion=0&_userid=1915929&md5=136de56ba50e2ac048c3b19cb8b371e8

4.Isotopic Analysis of Lithium by Atomic Absorption Spectrophotometry
Wheat, J.A
Applied Spectroscopy, Volume 25, Issue 3, Pages 293-383 (May/June 1971) , pp. 328-330(3)
http://chinesesites.library.ingentaconnect.com/content/sas/sas/1971/00000025/00000003/art00007

5.The determination of lithium isotope abundances with a dual-beam atomic absorption spectrometer
J. F. Chapman and L. S. Dale
Analytica Chimica Acta
Volume 87, Issue 1, November 1976, Pages 91-95
  http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TF4-448Y0GS-B&_user=1915929&_coverDate=11%2F30%2F1976&_rdoc=10&_fmt=high&_orig=browse&_srch=doc-info(%23toc%235216%231976%23999129998%23269098%23FLP%23display%23Volume)&_cdi=5216&_sort=d&_docanchor=&_ct=37&_acct=C000055340&_version=1&_urlVersion=0&_userid=1915929&md5=0dd2c7061b792fa192d3b00eeb17477a

6.The atomic absorption spectrometric determination of lithium isotope abundances by direct measurement of the absorbance ratio
J. F. Chapman, L. S. Dale and H. J. Fraser
Analytica Chimica Acta
Volume 116, Issue 2, 1 May 1980, Pages 427-431
  http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TF4-44GGX21-T&_user=1915929&_coverDate=05%2F01%2F1980&_rdoc=23&_fmt=high&_orig=browse&_srch=doc-info(%23toc%235216%231980%23998839997%23274390%23FLP%23display%23Volume)&_cdi=5216&_sort=d&_docanchor=&_ct=24&_acct=C000055340&_version=1&_urlVersion=0&_userid=1915929&md5=1073e490f60d8a9a158da7b2da8f4e7e