Here at Zacks, our focus is on the proven Zacks Rank system, which emphasizes earnings estimates and estimate revisions to find great stocks. Nevertheless, we are always paying attention to the latest value, growth, and momentum trends to underscore strong picks.Considering these trends, value investing is clearly one of the most preferred ways to find strong stocks in any type of market. Value investors use fundamental analysis and traditional valuation metrics to find stocks that they believe are being undervalued by the market at large.Zacks has developed the innovative Style Scores system to highlight stocks with specific traits. For example, value investors will be interested in stocks with great grades in the "Value" category. When paired with a high Zacks Rank, "A" grades in the Value category are among the strongest value stocks on the market today.One company to watch right now is Northern Oil and Gas (NOG). NOG is currently holding a Zacks Rank of #2 (Buy) and a Value grade of A. The stock holds a P/E ratio of 3.52, while its industry has an average P/E of 6.39. NOG's Forward P/E has been as high as 5.57 and as low as 2.65, with a median of 3.55, all within the past year.Finally, we should also recognize that NOG has a P/CF ratio of 3.07. This data point considers a firm's operating cash flow and is frequently used to find companies that are undervalued when considering their solid cash outlook. NOG's current P/CF looks attractive when compared to its industry's average P/CF of 8.30. Over the past year, NOG's P/CF has been as high as 50.89 and as low as -8.37, with a median of 6.70.If you're looking for another solid Oil and Gas - Exploration and Production - United States value stock, take a look at W&T Offshore (WTI). WTI is a # 2 (Buy) stock with a Value score of A.W&T Offshore sports a P/B ratio of -18.53 as well; this compares to its industry's price-to-book ratio of 3.34. In the past 52 weeks, WTI's P/B has been as high as -1.48, as low as -23.39, with a median of -3.23.These are just a handful of the figures considered in Northern Oil and Gas and W&T Offshore's great Value grade. Still, they help show that the stock is likely being undervalued at the moment. Add this to the strength of its earnings outlook, and we can clearly see that NOG and WTI is an impressive value stock right now. Special Report: The Top 5 IPOs for Your Portfolio Today, you have a chance to get in on the ground floor of one of the best investment opportunities of the year. As the world continues to benefit from an ever-evolving internet, a handful of innovative tech companies are on the brink of reaping immense rewards - and you can put yourself in a position to cash in. One is set to disrupt the online communication industry. Brilliantly designed for creating online communities, this stock is poised to explode when made public. With the strength of our economy and record amounts of cash flooding into IPOs, you don’t want to miss this opportunity.>>See Zacks’ Hottest IPOs NowWant the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Northern Oil and Gas, Inc. (NOG): Free Stock Analysis Report W&T Offshore, Inc. (WTI): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research