Michael Gouby authored an EXCELLENT book which he refers to on his website..... And is deovted to just the BRONZE PENNIES.... Michael Freeman's book, last published in 1985, with a reprint reported to be in the works, is the accepted authority on BRONZE coinage Peck is the accepted work on Copper, Bronze, and Tin.... There is also the SATIN reference (by John Jerrams), which covers BRONZE PENNIES from 1860-1865 NONE of these as ABSOLUTELY COMPLETE, as there are just too many minor varieties to be catalogued..... Most of the minor variants have no significant premium, although there ARE several EXTREMELY RARE varieties that do command an EXTREME PREMIUM..... and of course there are those that fall between.... I specialize primarily in BRONZE pennies and half-pennies, although I also collect farthings and the same denominations in Copper also...... Please feel free to contact me, if I can be of any assistance...... PM me and I'll give you my email address, and you can send me any images that you need to.... Best of Luck.....