Besides online sources, such as the Lawncare.org or Lovethegarden.com, there are some books on the topic of lawn care, such as "The Lawn Bible." The online sources are often free.
Lawncare.org offers its readers the advice of professional lawn care providers. It hosts information for both homeowners trying to maintain their garden and aspiring landscapers who want to start a business in lawn maintenance. Lovethegarden.org provides information more focused on free time gardeners, and lawn care is one of the many topics it covers.
"The Lawn Bible" contains the life experience of the groundskeeper of the Fenway Park, David Mellor.