As a mod of this sub, I appreciate you looking out for this as it is a shady practice to say the least. That said, this is not a reference link--I don't even have an Amazon partner account. This is the link in the OP:
amazon.com/Wiha-26190-Phillips-Screwdriver-Professional/dp/B00018AO0W/ref=sr_1_3?s=industrial&ie=UTF8&qid=1446690360&sr=1-3&keywords=wiha+precision
What may have confused you is the segment that says "ref=sr_1_3". the "ref" keyword is just one used by Amazon to track where their site visitors come from, which in this case was via direct search for the keywords "wiha" and "precision".
The Amazon Associates Program you are referring to when you mention reference links tracks their users via the keyword "tag" in the url, followed by a unique identifier for that user that is typically a 7-digit number in the form XXXXX-20. An actual referral link would look like this:
Where the ASIN would be replaced by amazon's unique 10-digit product ID code, and Associates_ID would be that 7 digit tag that indicates who shared the link and would earn the commission.