function ShowHide(moreBookCriticalPraise, me)
    {
        moreBookCriticalPraise.style.display = "block";
        me.style.display = "none";
    }

	function isEmailAddress (string) {
        var addressPattern = /^\w+((-\w+)|(\.\w+))*\@[A-Za-z0-9]+((\.|-)[A-Za-z0-9]+)*\.[A-Za-z0-9]+$/;
        return addressPattern.test(string);
	}
    
    function isDate(dateStr) {
        var datePat = /^(\d{1,2})(\/|-)(\d{1,2})(\/|-)(\d{4})$/;
        var matchArray = dateStr.match(datePat); // is the format ok?

        if (matchArray == null) 
        {
          alert("Please enter date using the drop-down menus provided.");
          return false;
        }
    
        month = matchArray[1];
        day = matchArray[3];
        year = matchArray[5];
           
        if (month < 1 || month > 12) { // check month range
            alert("Month must be between 1 and 12.");
            return false;
        }

        if (day < 1 || day > 31) {
            alert("Day must be between 1 and 31.");
            return false;
        }

        if ((month==4 || month==6 || month==9 || month==11) && day==31) {
            alert("Month "+month+" doesn't have 31 days!")
            return false;
        }
        
        if (year < 1890)
        {
		      alert("Please enter a valid birth year");
		      return false;
        }

        if (month == 2) { // check for february 29th
            var isleap = (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));
            if (day > 29 || (day==29 && !isleap)) {
                alert("February " + year + " doesn't have " + day + " days!");
                return false;
            }
        }
        return true; // date is valid
      }