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: Experiments with analogues and derivatives of CCK - 5 - 8 demonstrated that the effectiveness of the beta - alanyl derivatives of CCK - 5 - 8 were enhanced and that they were equipotent with CCK - 8 - SE .
### Output Text:
Experiments with analogues and derivatives of CCK - 5 - 8 demonstrated that the effectiveness of the beta - alanyl derivatives of CCK - 5 - 8 were enhanced and that they were equipotent with <span class="chemical">CCK - 8</span> - SE . 