ZYBOOKS has raised a $4 million round of investment led by Bialla Venture Partners. Founded in San Francisco in 2012, zyBooks makes interactive digital resources for students majoring in computer science or engineering. The company plans to create more content, expand sales and marketing and add features. David Uri, a managing member of Bialla, will join zyBooks' board. In a press release, zyBooks claims that its 16 "zyBooks" are used at 300 universities by more than 80,000 students.