References in classic literature ?
'Hallo!' he shouted to him, 'what are you aiming at?
'Hallo!' he shouted to him, 'why are you carrying wood through a forest?'
Hallo! Put a flask of wine and the largest pipe in the little vaulted room behind the hall."
"Hallo, my friend!" he cries, and strikes his iron candlestick against the door.