function validate_required(field,alerttxt)
{
with (field)
  {
  if (value==null||value=="")
    {
    alert(alerttxt);return false;
    }
  else
    {
    return true;
    }
  }
}
function validate_email(field,alerttxt)
{
with (field)
  {
  apos=value.indexOf("@");
  dotpos=value.lastIndexOf(".");
  if (apos<1||dotpos-apos<2)
    {alert(alerttxt);return false;}
  else {return true;}
  }
}
function validate_form(thisform)
{
with (thisform)
  {
	  if (validate_required(yourName,"Please enter your name!")==false)
	  {yourName.focus();return false;}
	  if (validate_email(email,"Email must be filled out correctly!")==false)
	  {email.focus();return false;}
	  if (validate_required(ISBN1,"ISBN #1 Must be filled out")==false)
	  {ISBN1.focus();return false;}
  }
}