def remove_quotation_marks(source_string):
    """
    :param source_string: String from which quotation marks will be removed (but only the outermost).
    :return: String without the outermost quotation marks and the outermost white characters.
    """
    first = source_string.find('"')
    second = source_string[first+1:].rfind('"')
    return source_string[first+1: second+first+1][:].strip()