Radio buttons that are not visible as radio buttons (Bootstrap)

radio-test.html

<div class="row">		
	<div class="col-xs-12 text-center">
		<h2>Select version:</h2>
			<div class="btn-group" data-toggle="buttons">
				<label id="esv" class="btn btn-primary active">
				<input type="radio" autocomplete="off">ESV
				</label>
				<label id="kjv" class="btn btn-primary">		
				<input type="radio" autocomplete="off">KJV
				</label>
				<label id="nlt" class="btn btn-primary">
				<input type="radio" autocomplete="off">NLT
				</label>
			</div>
	</div>
</div>