def get_xref_plotids(drive):
    """Dictionary of Sites to PlotID keys

    Args:
      drive: authorized Google Drive API client

    Returns:
      dict
    """
    res = drive.files().list(q="title contains 'Plot Identifiers'").execute()
    data = {}
    for item in res["items"]:
        if item["mimeType"] != "application/vnd.google-apps.spreadsheet":
            continue
        siteid = item["title"].split()[0]
        data[siteid] = item["id"]
    return data