In form and fashion these pilgrims' signs are very various and a considerable literature exists upon the subject.
The literature in this field exists in a variety of conference and journal proceedings.
A substantial literature existed concerning them, going back to the 17th century, but their religious outlook and rituals were poorly understood.
A growing literature exists about women who suddenly remember late in life that, as children, they were sexually abused by their fathers.
It is true that virtually no literature exists for the smaller bassoons.
Significant literature exists, especially for trout flies, on the concepts of imitation.
But literature also exists in an atmosphere of constant rebellion.
A very large literature exists about the growth of business relationships in all sorts of areas.
We all know that, and lest we forget it, an entire literature exists to remind us.
Considerable literature exists on these matters, but commercial considerations often play a significant role.