TurboTax does have links to the source of entries in their Desktop version of the progam. With that version, you can work in the "Forms" mode and in many instances make entries directly on the lines on forms and schedules. You can use your mouse to highlight a form entry, then right click on that entry to bring up a host of options such as "data source", "About (this line)", "QuickZoom", etc...
Here is a link to the TurboTax desktop program: TurboTax desktop product
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