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The standardization of the magnetic instruments at Helwan observatory during 1907 / by H.E. Hurst.
- 522.1 H9664
- Hurst, H. E.
- National Printing Dept.,
- 1908.
- Cairo :
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A discussion of the observations on atmospherie electricity at Helwan observatory from march 1906 to february 1908 / by H.E. Hurst.
- 551.563 H9664
- Hurst, H. E.
- National Printing Department,
- 1909.
- Cairo :