I would treat that part as numbered references. See Formats 16.1.4, which states that such notes can appear at the foot of the page or at the margin. These notes are at the margin.
Begin the boxed material and use the numbered reference indicator [braille]77#a, [braille]77#b, etc. where indicated in the print. When this material is done, entered a closing box line and insert a blank line, because a closing box line is always followed by a blank line.
Continue to braille the material on this print page, even though you may want to insert a braille page break to accommodate the diagram material. When this PRINT page is completed add the separation line for notes (Formats 16.4.1).
Immediately following the separation line, HOW TO FIND MAIN IDEAS heading in cell 5. Immediately following that, braille the notes in 1-3 as given in this Formats section. In this case, shows the reference number first, even though it is not printed that way, because it is intended to be read that way and to accommodate Formats, which also speaks to how this material is read. [braille]77#a _.,/rategy ,id5tify etc.
Note that some of the reference numbers are repeated in the boxed material and should be brailled as printed. The actual reference notes are printed once and also should be brailled as printed.