Collins Chinese Dictionary Plus (3rd edition), 2011:
不遗(遺)余(餘)力 bù yí yú lì do one's utmost
- 足球俱乐(樂)部不遗(遺)余(餘)力地引进(進)外国(國)球星。 Zúqiú jùlèbù bù yí yú lì de yǐnjìn wàiguó qiúxīng. The football team did its utmost to attract foreign football stars.