Helfrich, John
Nationality: Undetermined, possibly 
(United States)
Identities and Authority Control
- pdbooks.info ID: 1523
John Helfrich Contributed to the Following:
| Title | Edition | Year of Publication | Role | Country of Publication | Possible Copyright Status | Available Online? | |||
|---|---|---|---|---|---|---|---|---|---|
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| The Condensed chemical dictionary | 1920 | Editor | |  | |  | |    
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| The Condensed chemical dictionary: a reference volume for all requiring quick access to a large amount of essential data regarding chemicals, and other substances used in manufacturing and laboratory work | 1919 | Editor | | | | | |
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