Tickets for Cornell hockey, Penn basketball, and Princeton basketball will go on sale 9 a.m. January 4 at the 60 Boylston St. ticket offices. Undergraduates may exchange Harvard athletic coupons for tickets at that time. According to officials at the ticket office, each person will be limited to exchanging only his own coupon, with an option to buy an adjacent ticket. No person will be allowed to exchange large numbers of coupons for blocks of tickets.