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| 0000080172-15-000027-index.html | 2015-11-13 16:00:48 | |
| 0000080172-15-000027.txt | 2015-11-13 16:00:48 | |
 0000080172-15-000027-xbrl.zip | 54264 | 2015-11-13 16:00:48 |
| FilingSummary.xml | 16719 | 2015-11-13 16:00:48 |
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| npk-20151004xex311.htm | 10836 | 2015-11-13 16:00:48 |
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| npk-20151004xex321.htm | 6085 | 2015-11-13 16:00:48 |
| npk-20151004xex322.htm | 6085 | 2015-11-13 16:00:48 |
| npk-20151004_cal.xml | 43156 | 2015-11-13 16:00:48 |
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| R9.htm | 182123 | 2015-11-13 16:00:48 |
| report.css | 2767 | 2015-11-13 16:00:48 |
| Show.js | 1410 | 2015-11-13 16:00:48 |