One great exercise to get started on Double stops is by Sevcik called Preparatory Exercises in Double Stopping Op.9 for the Violin. These exercises can be found on [ Ссылка ] under SHEET MUSIC and choose FREE VIOLIN STUDIES, ETUDES AND SOLOS
Here I go through no.3 which is exceptional for pinpointing intonation in advance, correcting when combining the interval and for finding the correct bow arm angle. This and many other tutorials found on Fiddlerman.com
