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| 0001064728-20-000026-index.html | 2020-08-07 21:16:53 | |
| 0001064728-20-000026.txt | 2020-08-07 21:16:53 | |
 0001064728-20-000026-xbrl.zip | 627172 | 2020-08-07 21:16:53 |
| btu-20200630.htm | 4009878 | 2020-08-07 21:16:53 |
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| report.css | 2767 | 2020-08-07 21:16:53 |
| Show.js | 1085 | 2020-08-07 21:16:53 |