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: A further 64 % reduction of hepatitis was observed , when NAA was given to ethanol / AAP - mice .
### Output Text:
A further 64 % reduction of hepatitis was observed , when <span class="chemical">NAA</span> was given to <span class="chemical">ethanol</span> / <span class="chemical">AAP</span> - mice . 