Microsoft says some Lumia 640s can't install Windows 10 Technical Preview for phones - Neowin
Lumia 640 XL LTE review: Big-screen features for a small-screen price - CNET
Microsoft's Lumia 640 and 640 XL: Budget Windows Phones with LTE
Microsoft Lumia 640 - Wikipedia
An unofficial Windows 10 Mobile branch guide
Windows Phone 8.1 vs. Windows 10 Mobile on Microsoft Lumia 640 XL
Amazon.com: Lumia 640 4G LTE Smartphone, 6764A with 8GB Memory Cell GoPhone - Black - Compatible with Microsoft Nokia 8.1 Phones -Carrier Locked to AT&T Wireless : Cell Phones & Accessories
New Windows 10 Mobile update list of eligible devices surfaces - Nokiapoweruser
Windows Phones Most Likely To Get Windows 10 Mobile RS2 Build Next Week
Here are all the devices that can upgrade to Windows 10 Mobile - MSPoweruser
Review: Microsoft Lumia 640 XL | WIRED
Microsoft Lumia 640 starts receiving Windows 10 update in Europe - GSMArena.com news
I can't access the store after updating to win 10 on my lumia 640 : r/windowsphone
Microsoft Lumia 640 LTE - Full phone specifications
Microsoft Lumia 640 XL review | Windows Central
The Lumia 640 and 640 XL can't handle Microsoft's feature-packed Windows 10 Fall Creators Update - MSPoweruser
The Lumia 640 and 640XL won't receive the Fall Creators Update
Microsoft Lumia 640 XL 8GB Unlocked GSM Quad-Core WIndows Smartphone RM-1066 | eBay
Official Windows 10 Mobile eligible devices list has batches of devices receiving the update - Nokiapoweruser
Microsoft Lumia 640 Review | TechSpot
My Lumia 640 on Windows 10 Mobile and 635 on Windows Phone 8.1 : r/windowsphone
You can install Windows 10 ARM on Lumia 950/XL with new third-party tool
Microsoft rolls out Windows 10 Mobile upgrade for select phones – GeekWire
