static public String iso639_2_to_iso639_1(String threeCharCode) throws UnsupportedEncodingException {
    	String lowercase=threeCharCode.toLowerCase(Locale.ENGLISH);
    	String iso639_1=iso639_2to1.get(lowercase);
        
        if (iso639_1==null)
            throw new UnsupportedEncodingException("Can't use ISO 639-2 language \"" + threeCharCode +"\"");
        
        return iso639_1;
    }