Apple ProDOS (English Wikipedia)

Weyhrich, Steven (2001-07-07). "Chapter 15: DOS 3.3, ProDOS & Beyond". Apple II History. Archived from the original on 2008-09-17. Retrieved 2003-06-27.
Weyhrich, Steven (2001-07-07). "Chapter 15: DOS 3.3, ProDOS & Beyond". Apple II History. Archived from the original on 2008-09-17. Retrieved 2003-06-27. Weyhrich source: Hunter, Skillman (February 1985). "Road Maps To Apple II Disks: DOS 3.3, CP/M, Pascal, and ProDOS". Call-A.P.P.L.E. Renton, Washington: Apple Pugetsound Program Library Exchange: 10–21. ISSN 8755-4909. OCLC 8898855.

vectronicsappleworld.com (Global: low place; English: low place)

"History of DOS 3.3 and ProDOS". Archived from the original on 2013-06-06. Retrieved 2013-08-28.

Weyhrich, Steven (2001-07-07). "Chapter 15: DOS 3.3, ProDOS & Beyond". Apple II History. Archived from the original on 2008-09-17. Retrieved 2003-06-27.
"History of DOS 3.3 and ProDOS". Archived from the original on 2013-06-06. Retrieved 2013-08-28.
Weyhrich, Steven (2001-07-07). "Chapter 15: DOS 3.3, ProDOS & Beyond". Apple II History. Archived from the original on 2008-09-17. Retrieved 2003-06-27. Weyhrich source: Hunter, Skillman (February 1985). "Road Maps To Apple II Disks: DOS 3.3, CP/M, Pascal, and ProDOS". Call-A.P.P.L.E. Renton, Washington: Apple Pugetsound Program Library Exchange: 10–21. ISSN 8755-4909. OCLC 8898855.

Weyhrich, Steven (2001-07-07). "Chapter 15: DOS 3.3, ProDOS & Beyond". Apple II History. Archived from the original on 2008-09-17. Retrieved 2003-06-27. Weyhrich source: Hunter, Skillman (February 1985). "Road Maps To Apple II Disks: DOS 3.3, CP/M, Pascal, and ProDOS". Call-A.P.P.L.E. Renton, Washington: Apple Pugetsound Program Library Exchange: 10–21. ISSN 8755-4909. OCLC 8898855.