var chap_array = new Array(
    ["Volume 5 Part 4",'5.4/01'],

    ["Volume 5 Part 3",'5.3/01'],

    ["Volume 5 Part 2",'5.2/01'],

    ["Volume 5 Part 1",'5.1/00-cover'],

    ["Volume 4 Part 4",'4.4/01'],

    ["Volume 4 Part 3",'4.3/01'],

    ["Volume 4 Part 2",'4.2/01'],

    ["Volume 4 Part 1",'4.1/00-cover'],

    ["Volume 3 Part 4",'3.4/01'],

    ["Volume 3 Part 3",'3.3/01'],

    ["Volume 3 Part 2",'3.2/01'],

    ["Volume 3 Part 1",'3.1/00-cover'],

    ["Volume 2 Part 4",'2.4/01'],

    ["Volume 2 Part 3",'2.3/01'],

    ["Volume 2 Part 2",'2.2/01'],

    ["Volume 2 Part 1",'2.1/00-cover'],

    ["Volume 1 Part 4",'1.4/01'],

    ["Volume 1 Part 3",'1.3/01'],

    ["Volume 1 Part 2",'1.2/01'],

    ["Volume 1 Part 1",'1.1/00-cover']
);
for (var i=0; i<chap_array.length; i++) {
    document.getElementById('id_chapter_1').options[i] = new Option(chap_array[i][0],chap_array[i][1]);
    if (document.getElementById('id_chapter_2')) {
        document.getElementById('id_chapter_2').options[i] = new Option(chap_array[i][0],chap_array[i][1]);
    }
}