Investors looking for stocks in the Technology Services sector might want to consider either Vasta Platform Limited (VSTA) or Thomson Reuters (TRI). But which of these two companies is the best option for those looking for undervalued stocks? Let's take a closer look.There are plenty of strategies for discovering value stocks, but we have found that pairing a strong Zacks Rank with an impressive grade in the Value category of our Style Scores system produces the best returns. The proven Zacks Rank emphasizes companies with positive estimate revision trends, and our Style Scores highlight stocks with specific traits.Vasta Platform Limited and Thomson Reuters are sporting Zacks Ranks of #2 (Buy) and #3 (Hold), respectively, right now. The Zacks Rank favors stocks that have recently seen positive revisions to their earnings estimates, so investors should rest assured that VSTA has an improving earnings outlook. But this is only part of the picture for value investors.Value investors also try to analyze a wide range of traditional figures and metrics to help determine whether a company is undervalued at its current share price levels.The Style Score Value grade factors in a variety of key fundamental metrics, including the popular P/E ratio, P/S ratio, earnings yield, cash flow per share, and a number of other key stats that are commonly used by value investors.VSTA currently has a forward P/E ratio of 24.94, while TRI has a forward P/E of 42.10. We also note that VSTA has a PEG ratio of 0.85. This popular metric is similar to the widely-known P/E ratio, with the difference being that the PEG ratio also takes into account the company's expected earnings growth rate. TRI currently has a PEG ratio of 5.26.Another notable valuation metric for VSTA is its P/B ratio of 0.55. Investors use the P/B ratio to look at a stock's market value versus its book value, which is defined as total assets minus total liabilities. By comparison, TRI has a P/B of 3.58.These are just a few of the metrics contributing to VSTA's Value grade of B and TRI's Value grade of D.VSTA has seen stronger estimate revision activity and sports more attractive valuation metrics than TRI, so it seems like value investors will conclude that VSTA is the superior option right now. Bitcoin, Like the Internet Itself, Could Change Everything Blockchain and cryptocurrency has sparked one of the most exciting discussion topics of a generation. Some call it the “Internet of Money” and predict it could change the way money works forever. If true, it could do to banks what Netflix did to Blockbuster and Amazon did to Sears. Experts agree we’re still in the early stages of this technology, and as it grows, it will create several investing opportunities. Zacks’ has just revealed 3 companies that can help investors capitalize on the explosive profit potential of Bitcoin and the other cryptocurrencies with significantly less volatility than buying them directly. See 3 crypto-related stocks now >>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 Vasta Platform Limited (VSTA): Free Stock Analysis Report Thomson Reuters Corp (TRI): Free Stock Analysis Report To read this article on Zacks.com click here.