function button1Out() { document.bt1.src="images/buttons/buttons_01.png"; }
function button1Over() { document.bt1.src="images/buttons/buttons_over_01.png"; }

function button2Out() { document.bt2.src="images/buttons/buttons_02.gif"; }
function button2Over() { document.bt2.src="images/buttons/buttons_over_02.gif"; }

function button3Out() { document.bt3.src="images/buttons/buttons_03.gif"; }
function button3Over() { document.bt3.src="images/buttons/buttons_over_03.gif"; }

function button4Out() { document.bt4.src="images/buttons/buttons_04.gif"; }
function button4Over() { document.bt4.src="images/buttons/buttons_over_04.gif"; }

function button5Out() { document.bt5.src="images/buttons/buttons_05.gif"; }
function button5Over() { document.bt5.src="images/buttons/buttons_over_05.gif"; }

function button6Out() { document.bt6.src="images/buttons/buttons_06.gif"; }
function button6Over() { document.bt6.src="images/buttons/buttons_over_06.gif"; }

function button7Out() { document.bt7.src="images/buttons/buttons_07.gif"; }
function button7Over() { document.bt7.src="images/buttons/buttons_over_07.gif"; }

function button8Out() { document.bt8.src="images/buttons/buttons_08.gif"; }
function button8Over() { document.bt8.src="images/buttons/buttons_over_08.gif"; }

function button9Out() { document.bt9.src="images/buttons/buttons_09.gif"; }
function button9Over() { document.bt9.src="images/buttons/buttons_over_09.png"; }

function button10Out() { document.bt10.src="images/buttons/buttons_10.png"; }
function button10Over() { document.bt10.src="images/buttons/buttons_over_10.png"; }