When you acquire such links make sure you do it from someone you trust first of all.If one of your "colleagues" gets slapped,most of the time,all their backlinks will be manually reviewed.This is why is important to work with people that you trust and knows their stuff.
Some of the other important aspects are
-Quality of the site
It's part of a network?If it is,dose it look like a real site?Dose it bring any traffic?etc etc
-OBL
You don't want your link on a page with 50-100 external links.
-Relevance
-OBL Relevance
Are your colleagues part of the same niche,or there is a clear sign that "references" aren't actually "references"
-Etc
-Etc