In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Valproic acid induced encephalopathy - - 19 new cases in Germany from 1994 to 2003 - - a side effect associated to VPA - therapy not only in young children .
### Output Text:
<span class="chemical">Valproic acid</span> induced encephalopathy - - 19 new cases in Germany from 1994 to 2003 - - a side effect associated to <span class="chemical">VPA</span> - therapy not only in young children . 