def find_missing_items(intList):
    """
    Returns missing integers numbers from a list of integers
    :param intList: list(int), list of integers
    :return: list(int),  sorted list of missing integers numbers of the original list
    """

    original_set = set(intList)
    smallest_item = min(original_set)
    largest_item = max(original_set)
    full_set = set(range(smallest_item, largest_item + 1))
    return sorted(list(full_set - original_set))