In Kent from the late-18th century many principle booksellers sold guides to the sights of their own towns and neighbourhoods. The printing and sale of such guidebooks, often illustrated with extra maps and engravings, were important elements in the work of provincial printers and booksellers, bringing a regular income from visitors. In larger places, such as Canterbury, there was strong competition between rival booksellers. Equally, these guides often carried advertisements for local businesses, which makes this category of publication an important source of information for researchers. However, because many publishers preferred not to print the date of publication for fear that their guide would quickly seem out of date, it has been difficult for bibliographers to provide definitive lists of what was published when, and by whom.