Original sentence: The official Internal Revenue Service web site contains references to specific code sections and case law, including  (duty to file returns in general);  (duty to file income tax returns in particular); and  (duty to pay tax at time return is required to be filed) and  (definition of gross income) and  (timing of duty to file)
Edited sentence: The official Internal Revenue Service web site contains references to selected specific code sections and case law, including  (duty to file returns in general);  (duty to file income tax returns in particular); and  (duty to pay tax at time return is required to be filed) and  (definition of gross income) and  (timing of duty to file)