Charles Porter G.. Theological Education by Extension workbooks which present the important points of each book of the Old Testament and emphasizes the unity which exists between the books.

• Editorial Bautista Independiente
• Spiral
• Vol. 1, Introduction & Genesis, 195 pages, ISBN# 978-1-879892-67-5
• Vol. 2, Exodus – Deuteronomy, 277 pages, ISBN# 978-1-879892-74-3
• Vol. 3, Joshua – 2 Chronicles, 244 pages, ISBN# 978-1-879892-79-8
• Vol. 4, Ezra – Song of Solomon, 289 pages, ISBN# 978-1-879892-81-1
• Vol. 5, Isaiah – Ezekiel, 282 pages, ISBN# 978-1-879892-83-5
• Vol. 6, Daniel – Malachi, 320 pages, ISBN# 978-1-879892-85-9

Digital PDF documents

• Vol. 1, Introduction & Genesis, ISBN# 978-1-932607-57-4
• Vol. 2, Exodus – Deuteronomy, ISBN# 978-1-932607-58-1
• Vol. 3, Joshua – 2 Chronicles, ISBN# 978-1-932607-59-8
• Vol. 4, Ezra – Song of Solomon, ISBN# 978-1-932607-60-4
• Vol. 5, Isaiah – Ezekiel, ISBN# 978-1-932607-61-1
• Vol. 6, Daniel – Malachi, ISBN# 978-1-932607-62-8