Works designed and priced for a broad public which included but was not exclusively composed of the poorer and less well-educated and works printed for the education of the young were produced in very large numbers during the sixteenth and seventeenth centuries. The basic printed aids to literacy included the hornbook, the ABC with the catechism, and the primer; typical ABCs included the Lord's Prayer, the Creed, and the Ten Commandments. Some school books were part of the privileged monopoly of the universities of Oxford and Cambridge, which themselves often granted rights of publication to the Company in return for money payments. During the seventeenth century, almanacs were published for distinctive occupational groups, first mariners and seafarers, later lawyers, clergy, farriers, chapmen and constables. Sixteenth- and seventeenth-century ballads had a far wider range of references than chapbooks. Tessa Watt has provided a survey of all forms of cheap print in relation to popular piety for the period 1550 to 1640.