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: Objectives of the current study were to compare results between Sprague - Dawley ( SD ) and Wistar strains when ASA is administered on GD 9 , 10 , or 11 ; to compare the malformation patterns following single and multiple dosings during organogenesis in SD rats ; and to test the hypothesis that maternal gastrointestinal toxicity confounds the detection of low incidence malformations with ASA when a multiple dosing paradigm is used .
### Output Text:
Objectives of the current study were to compare results between Sprague - Dawley ( SD ) and Wistar strains when <span class="chemical">ASA</span> is administered on GD 9 , 10 , or 11 ; to compare the malformation patterns following single and multiple dosings during organogenesis in SD rats ; and to test the hypothesis that maternal gastrointestinal toxicity confounds the detection of low incidence malformations with <span class="chemical">ASA</span> when a multiple dosing paradigm is used . 