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: The analogues CCK - 8 - SE and CCK - 8 - NS ( dose range 0 . 2 - 6 . 4 mumol / kg ) and caerulein dose range 0 . 1 - 0 . 8 mumol / kg ) showed bell - shaped dose - effect curves , with the greatest maximum inhibition for CCK - 8 - NS .
### Output Text:
The analogues <span class="chemical">CCK - 8</span> - SE and <span class="chemical">CCK - 8</span> - NS ( dose range 0 . 2 - 6 . 4 mumol / kg ) and <span class="chemical">caerulein</span> dose range 0 . 1 - 0 . 8 mumol / kg ) showed bell - shaped dose - effect curves , with the greatest maximum inhibition for <span class="chemical">CCK - 8</span> - NS . 