The Convince & Convert
http://www.convinceandconvert.com/category/social-media-strategy/

TopRank Marketing
http://www.toprankblog.com/category/social-media/

The Portent Blog
https://www.portent.com/blog/

Sugarrae
https://sugarrae.com/online-marketing/social-media/

Adam Riemer Marketing
https://www.adamriemer.me/category/social-media/

Marketing Forward
http://www.experian.com/blogs/marketing-forward/tag/social-marketing/

MarketingProfs
https://www.marketingprofs.com/marketing/library/100/social-media

Marketing Land
https://marketingland.com/library/channel/social-media-marketing

Search Engine Watch
https://searchenginewatch.com/category/social/

The Daily Egg
https://www.crazyegg.com/blog/category/social-media-marketing/