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: METHODS : The cases were all patients entering the local dialysis program because of ESRD in the study area between June 1 , 1995 and November 30 , 1997 .
### Output Text:
METHODS : The cases were all patients entering the local dialysis program because of ESRD in the study area between June 1 , 1995 and November 30 , 1997 . 