function init_events(b,d,a,c){document.onkeydown=function(g){g=g||window.event;var f=g.keyCode||g.which;if(c&&39==f){if(d){window.location=d}return false}else{if(a&&37==f){if(b){window.location=b}else{alert("This is the first page of this series.")}return false}}};document.onclick=function(g){g=g||window.event;var f=g.target||g.srcElement;switch(f.id){case"btn-back-1":case"btn-back-2":if(a&&b){window.location=b;return false}break;case"btn-next-1":case"btn-next-2":if(c&&d){window.location=d;return false}break}}}try{do_init_events()}catch(e){};