Kovan LTC/USD Price feed for Chainlink. Deploy using: https://remix.ethereum.org/#version=soljson-v0.6.7+commit.b8d736ae.js&optimize=false&evmVersion=null&gist=8f1132c1c3062203c774cd09e3a89b8e

HistoricalPriceConsumerV3.sol

/** This example code is designed to quickly deploy an example contract using Remix.
 *  If you have never used Remix, try our example walkthrough: https://docs.chain.link/docs/example-walkthrough
 *  You will need testnet ETH and LINK.
 *     - Kovan ETH faucet: https://faucet.kovan.network/
 *     - Kovan LINK faucet: https://kovan.chain.link/
 */

pragma solidity ^0.6.7;

import "https://github.com/smartcontractkit/chainlink/blob/master/evm-contracts/src/v0.6/interfaces/AggregatorV3Interface.sol";

contract HistoricalPriceConsumerV3 {

    AggregatorV3Interface internal priceFeed;

    /**
     * Network: Kovan
     * Aggregator: LTC/USD
     * Address: 0xCeE03CF92C7fFC1Bad8EAA572d69a4b61b6D4640
     */
    constructor() public {
        priceFeed = AggregatorV3Interface(0xCeE03CF92C7fFC1Bad8EAA572d69a4b61b6D4640);
    }

    /**
     * Returns the latest price
     */
    function getHistoricalPrice(uint80 roundsBack) public view returns (int256) {
        (uint80 roundId,,,,) = priceFeed.latestRoundData();
        uint80 historicalRoundId = roundId - roundsBack;
        (
            uint80 id, 
            int price,
            uint startedAt,
            uint timeStamp,
            uint80 answeredInRound
        ) = priceFeed.getRoundData(historicalRoundId);
        return price;
    }
}