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 total of 66 children from 16 Pediatric Oncology Group institutions with " standard - risk " acute lymphoblastic leukemia , 1 . 00 to 9 . 99 years at diagnosis , without evidence of CNS leukemia at diagnosis were enrolled on ACCL0131 : 28 from P9201 and 38 from P9605 .
### Output Text:
A total of 66 children from 16 Pediatric Oncology Group institutions with " standard - risk " acute lymphoblastic leukemia , 1 . 00 to 9 . 99 years at diagnosis , without evidence of CNS leukemia at diagnosis were enrolled on ACCL0131 : 28 from P9201 and 38 from P9605 . 