Amazon | Location Estimation in a 3D Environment using RFID Tags: Mutliple tag readers with known location and Concept of Trilateration is used to estimate the physical location of an individual tag
Amazon.com: YARONGTECH RFID Sticker tag 13.56mhz Round 25mm Adhesive Back -50pcs : Office Products
BMES EM18 125Khz RFID Reader Module + 5 x 125Khz RFID Tags : Amazon.in: Industrial & Scientific
Amazon.com: UHF RFID Tag Impinj H47 True 3D Sticker 860-960MHZ Monza 4 915M EPC C1G2 ISO18000-6C can be Used to RFID tag and Label (Pack of 20) : Electronics
Amazon.com: 125khz RFID Writable rewritable T5577 fob tag for RFID Writer (Pack of 10) (Black) : Electronics
Impinj Surges: Is Amazon Using Their RFID Tags? | Barron's
Coin type 125KHZ RFID Card | EM RFID Tag Cards/size:25MM with Sticker 2PCS : Amazon.in: Industrial & Scientific
Amazon Unveils RFID Technology for 'Shop and Go' Consumers
Amazon.com: YARONGTECH 5pcs Read Only RFID 125Khz EM4100 Tags ID Keychain Access Fob : Electronics
Amazon.com: 13.56mhz tag,RFID Key,Iso14443a RFID tag (Pack of 10) : Industrial & Scientific
After testing a few 125 KHz RFID tags from Amazon, I found these to be the best. (More in comments below) : r/flipperzero