With links to the complete edition of Euclid with pictures in Java by David Joyce, and the well known comments from Heath's edition at the Perseus collection of Greek classics.

Introductory
David Joyce's Introduction to Book III

Definitions from Book III
Byrne's edition - Definitions 1, 2, 3, 4
Byrne's edition - Definitions 5, 6, 7, 8, 9
Byrne's edition - Definition 10
David Joyce's Euclid
Heath's comments

Proposition III.1
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.2
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.3
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.4
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.5
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.6
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.7
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.8
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.9
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.10
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.11
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.12
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.13
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.14
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.15
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.16
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.17
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.18
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.19
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.20
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.21
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.22
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.23
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.24
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.25
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.26
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.27
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.28
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.29
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.30
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.31
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.32
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.33
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.34
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.35
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.36
Byrne's edition
David Joyce's Euclid
Heath's comments

Proposition III.37
Byrne's edition
David Joyce's Euclid
Heath's comments