Работа с данными файлов Excel .xlsx. Чтение и вывод данных с использованием модуля openpyxl

Traceback (most recent call last):
  File "E:\Sys\Program Files\Python 2.7.8\HCM", line 4, in <module>
    ws1['B2']=1
TypeError: list indices must be integers, not str

import openpyxl
wb = openpyxl.load_workbook(filename='E:/Adjustment factor.xlsx')
ws1=["u'"]
c= ws1['D3']

print wb.get_sheet_names()

import openpyxl
wb = openpyxl.load_workbook(filename='E:/raz.xlsx')
print (wb.get_sheet_names())
ws1=["u'"]
c= ws1['D3']
print c

import openpyxl
import openpyxl
wb = openpyxl.load_workbook(filename='E:/raz.xlsx')
print (wb.get_sheet_names())
ws1=wb["density"]
c= ws1['D3'].value
print c

In [1]: import openpyxl
 
In [2]: wb = openpyxl.load_workbook(filename='raz.xlsx')
 
In [3]: wb.get_sheet_names()
Out[3]: ['Лист1', 'Лист2', 'Лист3']
 
In [4]: ws = wb['Лист1']
 
In [5]: ws
Out[5]: <Worksheet "Лист1">
 
In [6]: ws['D3']
Out[6]: <Cell Лист1.D3>
 
In [7]: ws['D3'].val()
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-7-8b0688d35f12> in <module>()
----> 1 ws['D3'].val()
 
AttributeError: 'Cell' object has no attribute 'val'
 
In [8]: ws['D3'].value
Out[8]: 1