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. 2012 Apr 13;7(4):e35254. doi: 10.1371/journal.pone.0035254

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Chen et al.

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.

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For the 3,883 drugs in , 3,295 belong to one class, 370 to two classes, 110 to three classes, 37 to four classes, 27 to five classes, 44 to six classes, and none to seven or more classes.

Inline graphic — For the 3,883 drugs in , 3,295 belong to one class, 370 to two classes, 110 to three classes, 37 to four classes, 27 to five classes, 44 to six classes, and none to seven or more classes.