Use canonical EIP reference format

contracts/introspection/ERC165Checker.sol

@@ -3,7 +3,7 @@ pragma solidity ^0.5.2;
 /**
  * @title ERC165Checker
  * @dev Use `using ERC165Checker for address`; to include this library
- * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-165.md
+ * https://eips.ethereum.org/EIPS/eip-165
  */
 library ERC165Checker {
     // As per the EIP-165 spec, no interface should ever match 0xffffffff

contracts/introspection/IERC165.sol

@@ -2,7 +2,7 @@ pragma solidity ^0.5.2;
 
 /**
  * @title IERC165
- * @dev https://github.com/ethereum/EIPs/blob/master/EIPS/eip-165.md
+ * @dev https://eips.ethereum.org/EIPS/eip-165
  */
 interface IERC165 {
     /**

contracts/mocks/ERC165/ERC165InterfacesSupported.sol

@@ -3,7 +3,7 @@ pragma solidity ^0.5.2;
 import "../../introspection/IERC165.sol";
 
 /**
- * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-214.md#specification
+ * https://eips.ethereum.org/EIPS/eip-214#specification
  * From the specification:
  * > Any attempts to make state-changing operations inside an execution instance with STATIC set to true will instead
  * throw an exception.

contracts/mocks/OwnableInterfaceId.sol

@@ -5,7 +5,7 @@ import "../ownership/Ownable.sol";
 /**
  * @title Ownable interface id calculator.
  * @dev See the EIP165 specification for more information:
- * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-165.md#specification
+ * https://eips.ethereum.org/EIPS/eip-165#specification
  */
 contract OwnableInterfaceId {
     function getInterfaceId() public pure returns (bytes4) {

contracts/token/ERC20/ERC20.sol

@@ -7,7 +7,7 @@ import "../../math/SafeMath.sol";
  * @title Standard ERC20 token
  *
  * @dev Implementation of the basic standard token.
- * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
+ * https://eips.ethereum.org/EIPS/eip-20
  * Originally based on code by FirstBlood:
  * https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
  *

contracts/token/ERC20/IERC20.sol

@@ -2,7 +2,7 @@ pragma solidity ^0.5.2;
 
 /**
  * @title ERC20 interface
- * @dev see https://github.com/ethereum/EIPs/issues/20
+ * @dev see https://eips.ethereum.org/EIPS/eip-20
  */
 interface IERC20 {
     function transfer(address to, uint256 value) external returns (bool);

contracts/token/ERC721/ERC721.sol

@@ -9,7 +9,7 @@ import "../../introspection/ERC165.sol";
 
 /**
  * @title ERC721 Non-Fungible Token Standard basic implementation
- * @dev see https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
+ * @dev see https://eips.ethereum.org/EIPS/eip-721
  */
 contract ERC721 is ERC165, IERC721 {
     using SafeMath for uint256;

contracts/token/ERC721/ERC721Enumerable.sol

@@ -6,7 +6,7 @@ import "../../introspection/ERC165.sol";
 
 /**
  * @title ERC-721 Non-Fungible Token with optional enumeration extension logic
- * @dev See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
+ * @dev See https://eips.ethereum.org/EIPS/eip-721
  */
 contract ERC721Enumerable is ERC165, ERC721, IERC721Enumerable {
     // Mapping from owner to list of owned token IDs

contracts/token/ERC721/ERC721Full.sol

@@ -8,7 +8,7 @@ import "./ERC721Metadata.sol";
  * @title Full ERC721 Token
  * This implementation includes all the required and some optional functionality of the ERC721 standard
  * Moreover, it includes approve all functionality using operator terminology
- * @dev see https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
+ * @dev see https://eips.ethereum.org/EIPS/eip-721
  */
 contract ERC721Full is ERC721, ERC721Enumerable, ERC721Metadata {
     constructor (string memory name, string memory symbol) public ERC721Metadata(name, symbol) {

contracts/token/ERC721/IERC721Enumerable.sol

@@ -4,7 +4,7 @@ import "./IERC721.sol";
 
 /**
  * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
- * @dev See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
+ * @dev See https://eips.ethereum.org/EIPS/eip-721
  */
 contract IERC721Enumerable is IERC721 {
     function totalSupply() public view returns (uint256);

contracts/token/ERC721/IERC721Full.sol

@@ -6,7 +6,7 @@ import "./IERC721Metadata.sol";
 
 /**
  * @title ERC-721 Non-Fungible Token Standard, full implementation interface
- * @dev See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
+ * @dev See https://eips.ethereum.org/EIPS/eip-721
  */
 contract IERC721Full is IERC721, IERC721Enumerable, IERC721Metadata {
     // solhint-disable-previous-line no-empty-blocks

contracts/token/ERC721/IERC721Metadata.sol

@@ -4,7 +4,7 @@ import "./IERC721.sol";
 
 /**
  * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
- * @dev See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
+ * @dev See https://eips.ethereum.org/EIPS/eip-721
  */
 contract IERC721Metadata is IERC721 {
     function name() external view returns (string memory);