D-galactaro-1,5-lactone <=> D-galactaro-1,4-lactone
d-galactaro-1,5-lactone <=> d-galactaro-1,4-lactone
D-galactaro-1,5-lactone <=> D-galactaro-1,4-lactone
d-galactaro-1,5-lactone <=> d-galactaro-1,4-lactone