Textbox with multiple columns and rows using data from another sheet.

Dear Friends,

I have macro to fill textbox in multiple rows and columns. This works only if data is in same sheet. But my data is in another workbook sheet which i need to be used to fill textbox.
Can some one adjust my code to get data from closed workbook?

(code which i use is as below. Sample of file is also attached)

Private Sub UserForm_Initialize()
   
    'Set properties of listbox1
    With Me.ListBox1
        .BoundColumn = 1
        .ColumnCount = 3
        .ColumnHeads = True
        .TextColumn = True
        .RowSource = "Sheet1!A2:C15"
        .ListStyle = fmListStyleOption
        .ListIndex = 0
    End With

End Sub

Thanks in advance.