There are some online collections available at Haverford for early modern printed texts. They reproduce every page in a book and are searchable by word and phrase.
Those that have been edited, reprinted in facsimiles, or transferred to microfilm can be borrowed through E-Z Borrow or interlibrary loan if they are not in Tripod. Many of them will be listed in WorldCat under subject terms and the word "sources." For example, the search child* england history sources produces results including:
Mother's Advice Books. Ashgate, 2002.
Books printed in the 17th or 18th century are kept in libraries' rare book collections. You can go to Bryn Mawr, the University of Pennsylvania, and other local libraries to see these books.