Example I took was my ```/etc/apt/sources.list.d/puppetlabs.list``` after I install puppetlabs package from http://apt.puppetlabs.com/ (e.g http://apt.puppetlabs.com/puppetlabs-release-wheezy.deb) and the file contained 3 repo (including a commented one) :

```
# cat /etc/apt/sources.list.d/puppetlabs.list                                                                                           </ 17:07:47
# Puppetlabs products
deb http://apt.puppetlabs.com wheezy main
deb-src http://apt.puppetlabs.com wheezy main

# Puppetlabs dependencies
deb http://apt.puppetlabs.com wheezy dependencies
deb-src http://apt.puppetlabs.com wheezy dependencies

# Puppetlabs devel (uncomment to activate)
# deb http://apt.puppetlabs.com wheezy devel
# deb-src http://apt.puppetlabs.com wheezy devel
```
So I just followed that, maybe it could be easier to update in case you want to change dependencies repo ?