The optional basso continuo part is available only as a free download here:

The Twelve Sonatas Opus 6 for Violin and Continuo known as “Trattenimenti Armonici per Camera” (An Entertainment of Harmony) was first published in 1712. This spacious new series is based faithfully on Professor Michael Talbot’s scholarly 1979 European Archive edition and includes an illuminating Preface and Critical Commentary.

Volume 1: Op. 6 nos. 1-4. Four Sonatas: C, G minor, B flat and D minor.
The 4th movt from Sonata in D minor (Op. 6 No. 4) selected by ABRSM for Violin Grade 5, 2012-2015.

Contents

Sonata in B flat major, Op.6 no.3
Sonata in C major, Op.6 no.1
Sonata in D minor, Op.6 no.4
Sonata in G minor, Op.6 no.2