A notable proxy-advisory firm on Monday said shareholders should support Ron Burkle’s director slate for Barnes & Noble, giving the Los Angeles billionaire investor some crucial support before a crucial shareholders’ meeting next week.

Burkle’s Yucaipa Cos. is the New York book store chain’s second-largest shareholder, controlling 18.8 percent of common shares. He has been fighting for control of the company with Barnes & Noble co-founder and Chairman Leonard Riggio, who controls 28.2 percent of shares. The company’s annual meeting is scheduled for Sept. 28.

“We believe the dissidents have demonstrated a compelling case that change in the Barnes & Noble board is warranted,” said Institutional Shareholder Services, citing the company’s “deteriorating operating performance, poor shareholder return and less-than-enthusiastic analyst recommendations.”

However, Barnes & Noble received support on Monday from a third proxy advisor, Proxy Governance Inc., which noted that the company’s nominees included two outsiders who would bring fresh blood to the board. Last week, the company received support from advisory firms Glass Lewis and Egan-Jones Proxy Services.