Ten books introducing alternative vowel spellings.
Book 1: ‘ae’: ay, ai, a, a-e, ea, ey
Book 2: ‘ee’: ee, ea, y, e, ie, e-e, ei
Book 3: ‘oe’: ow, oa, oe, o-e, o
Book 4: ‘er’: , er, ir, ur,or, ear
Book 5: ‘ow”oi’: ow,ou & oi, oy
Book 6: ‘oo’: oo, ue, u-e, ew, ou, u
Book 7:‘ie’:  igh, ie, i-e, i, y
Book 8: ‘or’:or, ore, a, aw, awe, au, ar, al, ough
Book 9: ‘air’: air, are, ear, ere, eir
Book 10: ‘ar’: ar, a, al, au, ear