Beth,like we always say and it has proven to be true,an indoor cat does not go very far from home.
Check all your neighbors backyards,bushes,garages..go out at night when things are quieter,with his favorite treat,bring a flashlight,as the first thing you'll see is the cats eyes,if he's hiding in a bush.
Print out posters plaster them everywhere,visit all the shelters in Burlington,often a phonecall is not enough,put posters in vet-offices.
That's all I can think of for now,good luck finding him,I am 99,9% sure he is not far from home.