ASIMOV, Isaac (1920-1992). Pair of Signed, Limited Editions, including: Nightfall [with Robert Silverberg]. Garden City, NY: Doubleday, [1990]. 8vo. 339, [3, blank] pp. Publisher's quarter burgundy cloth over boards, front board and spine stamped in gilt, publisher's slipcase with pictorial label. Fine. FIRST EDITION, #186/750 SIGNED BY ASIMOV AND SILVERBERG. And: Pebble in the Sky. Garden City, NY: Doubleday, [1990]. Publisher's binding, dust jacket, slipcase, sealed in publisher's shrinkwrap. Fine. 4OTH ANNIVERSARY EDITION, ONE OF 1,500 COPIES SIGNED BY ASIMOV. From the renowned personal collection of Dr. George D. Lacy. Measurements: 9 x 6 x 2.