Here at Zacks, we focus on our proven ranking system, which places an emphasis on earnings estimates and estimate revisions, to find winning stocks. But we also understand that investors develop their own strategies, so we are constantly looking at the latest trends in value, growth, and momentum to find strong companies for our readers.Looking at the history of these trends, perhaps none is more beloved than value investing. This strategy simply looks to identify companies that are being undervalued by the broader market. Value investors use fundamental analysis and traditional valuation metrics to find stocks that they believe are being undervalued by the market at large.Luckily, Zacks has developed its own Style Scores system in an effort to find stocks with specific traits. Value investors will be interested in the system's "Value" category. Stocks with both "A" grades in the Value category and high Zacks Ranks are among the strongest value stocks on the market right now.One company value investors might notice is Greif (GEF). GEF is currently holding a Zacks Rank of #1 (Strong Buy) and a Value grade of A. The stock is trading with P/E ratio of 11.29 right now. For comparison, its industry sports an average P/E of 16.04. GEF's Forward P/E has been as high as 16.95 and as low as 9.05, with a median of 13.26, all within the past year.GEF is also sporting a PEG ratio of 1.13. This popular figure is similar to the widely-used P/E ratio, but the PEG ratio also considers a company's expected EPS growth rate. GEF's industry currently sports an average PEG of 1.85. Over the last 12 months, GEF's PEG has been as high as 1.70 and as low as 0.91, with a median of 1.33.Value investors also love the P/S ratio, which is calculated by simply dividing a stock's price with the company's sales. This is a popular metric because sales are harder to manipulate on an income statement, so they are often considered a better performance indicator. GEF has a P/S ratio of 0.61. This compares to its industry's average P/S of 1.36.These figures are just a handful of the metrics value investors tend to look at, but they help show that Greif is likely being undervalued right now. Considering this, as well as the strength of its earnings outlook, GEF feels like a great value stock at the moment. Infrastructure Stock Boom to Sweep America A massive push to rebuild the crumbling U.S. infrastructure will soon be underway. It’s bipartisan, urgent, and inevitable. Trillions will be spent. Fortunes will be made. The only question is “Will you get into the right stocks early when their growth potential is greatest?” Zacks has released a Special Report to help you do just that, and today it’s free. Discover 7 special companies that look to gain the most from construction and repair to roads, bridges, and buildings, plus cargo hauling and energy transformation on an almost unimaginable scale.Download FREE: How to Profit from Trillions on Spending for Infrastructure >>Want 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 Greif, Inc. (GEF): Free Stock Analysis Report To read this article on Zacks.com click here.