If you need immediate Medical, Police, Fire, or other emergency response: DIAL 911
If you need "after hours" emergency veterinary assistance:
You may LOOK in the Yellow Pages under "Veterinarians" or other likely headings in the same part of the Yellow Pages: for example, Veterinary Emergency Services, etc.
Some veterinary clinics/hospitals offer 24-hour emergency services.
You may try looking-up a veterinarian under his/her name in the White Pages.
Or, search the Internet for veterinary clinics/hospitals or a particular veterinarian at google.com or anywho.com.