Book lists

• Hands pointing to text in square after cubes
• Textbook adjuncts
• The Dow and the Nikkei
• Back-of-the-book conveniences
• The Dow and the Nikkei 225
• Book parts
• Back-of-the-book readings

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
according to OED, the plural form of index preferable in scientific and mathematical senses of that word.

Wiktionary Word definitions in Wiktionary
n. (en-irregular index nodot=1) (gloss: when used in the sense of a key to locate an element in a list, vector or matrix in computing or mathematics)