30 books • 2 series
6000 Exercises to Improve your English Language Spelling Skills in Just 30 Days while you Learn 4000 New English Words (Learn English Spellings, #7)
Improve your Spellings (Learn English Spellings, #5)
Ultimate Spelling Bee (Learn English Spellings, #4)
English Spelling Quiz (Learn English Spellings, #3)
Spelling Magic (Learn English Spellings, #2)
Misspelling Quiz (Learn English Spellings, #1)