Houghton Mifflin Harcourt Company (NasdaqGS:HMHC) a publisher of education materials and research, is exploring a potential sale, according to people familiar with the matter. The Boston-based company is working with an adviser, said the people, who asked not to be identified because they weren't authorized to speak publicly. Private equity firms are exploring bids for the company, the people said.

No final decision has been made and the company could opt to remain independent, they added.