function switch1() 
{
var option=['text_allemaal','boek_allemaal'];
for(var i=0; i<option.length; i++) 
{ obj=document.getElementById(option[i]);
obj.className=(obj.className=="visible")? "hidden" : "visible"; }
}

function switch2() 
{
var option=['text_delict','boek_delict'];
for(var i=0; i<option.length; i++) 
{ obj=document.getElementById(option[i]);
obj.className=(obj.className=="visible")? "hidden" : "visible"; }
}

function switch3() 
{
var option=['text_omkijken','boek_omkijken'];
for(var i=0; i<option.length; i++) 
{ obj=document.getElementById(option[i]);
obj.className=(obj.className=="visible")? "hidden" : "visible"; }
}

function switch4() 
{
var option=['text_mahui','boek_mahui'];
for(var i=0; i<option.length; i++) 
{ obj=document.getElementById(option[i]);
obj.className=(obj.className=="visible")? "hidden" : "visible"; }
}

function switch5() 
{
var option=['text_fragile','boek_fragile'];
for(var i=0; i<option.length; i++) 
{ obj=document.getElementById(option[i]);
obj.className=(obj.className=="visible")? "hidden" : "visible"; }
}
function switch6() 
{
var option=['text_metamorfose','boek_metamorfose'];
for(var i=0; i<option.length; i++) 
{ obj=document.getElementById(option[i]);
obj.className=(obj.className=="visible")? "hidden" : "visible"; }
}

function switch7() 
{
var option=['text_dialogues','boek_dialogues'];
for(var i=0; i<option.length; i++) 
{ obj=document.getElementById(option[i]);
obj.className=(obj.className=="visible")? "hidden" : "visible"; }
}

function switch8() 
{
var option=['text_brood','boek_brood'];
for(var i=0; i<option.length; i++) 
{ obj=document.getElementById(option[i]);
obj.className=(obj.className=="visible")? "hidden" : "visible"; }
}

function switch9() 
{
var option=['text_cameroun','boek_cameroun'];
for(var i=0; i<option.length; i++) 
{ obj=document.getElementById(option[i]);
obj.className=(obj.className=="visible")? "hidden" : "visible"; }
}

function switch10() 
{
var option=['text_katrina','boek_katrina'];
for(var i=0; i<option.length; i++) 
{ obj=document.getElementById(option[i]);
obj.className=(obj.className=="visible")? "hidden" : "visible"; }
}

function switch11() 
{
var option=['text_punt','boek_punt'];
for(var i=0; i<option.length; i++) 
{ obj=document.getElementById(option[i]);
obj.className=(obj.className=="visible")? "hidden" : "visible"; }
}

function switch12() 
{
var option=['text_monde','boek_monde'];
for(var i=0; i<option.length; i++) 
{ obj=document.getElementById(option[i]);
obj.className=(obj.className=="visible")? "hidden" : "visible"; }
}

function switch12() 
{
var option=['text_wpph','boek_wpph'];
for(var i=0; i<option.length; i++) 
{ obj=document.getElementById(option[i]);
obj.className=(obj.className=="visible")? "hidden" : "visible"; }
}


function switch13() 
{
var option=['text_marcus','boek_marcus'];
for(var i=0; i<option.length; i++) 
{ obj=document.getElementById(option[i]);
obj.className=(obj.className=="visible")? "hidden" : "visible"; }
}