Link to mentioned Solidity bug

Author: fulldecent

EIPS/eip-721.md

@@ -381,7 +381,7 @@ Example deeds implementations as of February 2018:
 
 Note: "Limited edition, collectible tokens" like [Curio Cards](https://mycuriocards.com/) and [Rare Pepe](https://rarepepewallet.com/) are *not* deeds. They're actually a collection of individual fungible tokens, each of which is tracked by its own smart contract with its own total supply (which may be `1` in extreme cases).
 
-The `onNFTReceived` function specifically works around old deployed contracts which may inadvertently return 1 (`true`) in certain circumstances even if they don't implement a function. By returning, and checking for, a magic value we are able to distinguish actual affirmative responses versus these `true`s.
+The `onNFTReceived` function specifically works around old deployed contracts [which may inadvertently return 1 (`true`)](http://solidity.readthedocs.io/en/develop/bugs.html#DelegateCallReturnValue) in certain circumstances even if they don't implement a function. By returning, and checking for, a magic value we are able to distinguish actual affirmative responses versus these `true`s.
 
 ## Test Cases