U.S. leading e-book publishers H1 2014, by published bestsellers

The source categorizes a a bestseller based on the following criteria: 1) Best-seller rank observed from the six top retailers (Kindle, Apple, Nook, Google, Kobo, Sony)
2) Lists observed for seven consecutive days (Sun. – Sat.)
3) Each appearance on a list gets an unweighted score based on the ranking
4) Ranking scores are logarithmically determined (i.e. top scores are much more valuable than lower scores)
5) Each retailer weighted by approximate market share as determined by the editors of Digital Book World and Iobyte Solutions
6) Additional appearance credit is awarded for appearing on multiple lists
7) Combined scores for the week determine final score for each title
8) Titles are ranked by final scores and also grouped into sub-lists by price (four separate price-band lists: $0 – $2.99; $3.00 – $7.99; $8.00 – $9.99; and $10.00 and above)
9) Minimum price that appeared at any point during the week on any retailer is used for determine price band (assumption that low price is an important driver of ranking)