"Early marriages from newspapers published in central New York; v. 01", is a manuscript prepared by William Martin Beauchamp (1830-1925) available free of charge at FamilySearch.
This book contains thousands of names listed in alphabetical order. Below is a sample of what is provided. The following are Leonard marriages, as recorded on page 112:
Alfred Leonard, Jr., of Clay, and Sarah Bruce, of Clay. At Oswego, (Aug. 8) 1846 (Onondaga Democrat)
Ann S. Leonard married Asa Barnes*
David H. Leonard (See Asa Barnes*)
David Leonard and Joanna Hannum. June 14, 1838 (St. James Church Record, Skaneateles)
Ezra Leonard and Mrs. Sarah Adams. At Skaneateles, Feb. 2, 1848. (Skaneateles Columbian)
Hiram J. Leonard of Lafayette and Sarah C. Lamson of Arcadia. At Arcadia, (Sept. 22) 1847. (Onondaga Democrat)
Jarvis Leonard of Vienna and Polly Bishop of Verona. At Verona, (April 23) 1820. (Onondaga Register)
Jennette Leonard (See George S. Hall**)
Samuel Leonard and Maria Austin. At Skaneateles (Nov. 24) 1819. (Onondaga Register)
*On page 11, regarding Asa Barnes: "Barnes, Asa, of Wisconsin, late of Pompey, and Ann S., daughter of David H. Leonard, of De Witt. At De Witt (Mar. 3), 1847. (Onondaga Democrat).
**On page 82, regarding George S. Hall: "Hall, George S. and Jennette Leonard. At Auburn, (Feb. 23) 1831. (Onondaga Register).
To find these newspapers, check out my Newspaper links. (Tip: FultonHistory.com is probably your best bet!)