source_type will filter by following source types:

1 = Twitter Tag
2 = InsTagram Tag
3 = Twitter User
4 = InsTagram User
5 = Facebook page
6 = Vine Tag
7 = Pinterest User
8 = Google+ Tag
9 = Flickr Tag
10 = Youtube Tag
11 = Tumblr Tag
12 = Google+ User
13 = Youtube channel
14 = Tumblr User
15 = Flickr User
16 = Rss
17 = LinkedIn User
18 = LinkedIn Page
19 = Vine User
20 = Twitter User Mention
21 = Twitter Geo Location
22 = InsTagram Geo Location
23 = InsTagram Location
24 = Facebook Visitor Posts
25 = Twitter timeline
26 = Pinterest Tag
27 = Flick Album
28 = Vimeo Tag
29 = DiffBot Crawlbot