Already heavily-backed textbook rental firm Chegg has added another $75 million. The company’s service, which lets students rent textbooks so they don’t have to buy them, has gained a big following on college campuses. One outside estimate puts the company’s sales this year at $130 million, up from $25 million in 2009. That growth has forced the two top college bookstore operators in the U.S., Barnes & Noble (NYSE: BKS) and Follett Higher Education Group, to launch their own competing textbook rental services.

Chegg most recently raised $112 million in debt and equity funding round last fall. This investment—which comes from a Hong Kong-based investment firm called Ace Limited, according to a report in AllThingsD, brings Chegg’s total funding to more than $200 million.

Chegg is led by former Yahoo (NSDQ: YHOO) COO Dan Rosensweig, who the company hired away from Activision (NSDQ: ATVI) last year.

Textbook Rental Firm Chegg Raises $75 Million More | paidContent.