The "Valley Vivaldi" summer chamber music series, presented by Pennsylvania Sinfonia Orchestra, continues July 19 at Wesley Church Bethlehem.

The program is a mix of instrumental works for small ensembles. Although the harp is not regularly represented in the Sinfonia's orchestra concerts, summer audiences greatly enjoy the addition of harp repertoire in "Valley Vivaldi." Harpist Frances Duffy, who is active who is active with orchestras in the Mid-Atlantic region and on Broadway, will perform in two pieces: "Sonata in G minor for Flute and Harp" by Carl P. E. Bach and "Trio Sonata in D for Harp, Flute and Viola" by Jean Leclair. Collaborating with Duffy will be Sinfonia's principal flutist Robin Kani.

J.S. Bach's "Concerto in D minor for Two Violins," BWV 1043, a familiar, masterful work for two well-matched violinists and accompanying strings, is often called the "Double Concerto." Sinfonia concertmaster Mary Ogletree and principal second violin Rebecca Brown are featured in this piece. Both musicians are frequent soloists for "Valley Vivaldi" and perform regularly with the Bach Festival Orchestra, Satori and the Sinfonia.

Oboist Cheryl Bishkoff has the lead role in the "Concerto in A for Oboe d'amore" by Baroque composer Georg Telemann. The concert opens with "Cello Sonata in B flat" by the series' namesake, Antonio Vivaldi. Cellist Naomi Gray will perform.

Orchestra personnel for the program include violinists Simon Maurer and Inna Eyzerovich, violist Agnès Maurer, double bassist Nancy Merriam and harpsichordist Allan Birney.

A reception with the musicians follows the concert.

The final "Valley Vivaldi" concert for summer 2015 is Aug. 16, also at Wesley Church Bethlehem. Along with Baroque pieces by J.S. Bach and Zelenka, the program will feature Antonio Vivaldi's "The Four Seasons." Violinist Paul Chou is guest soloist.

Tickets: PASinfonia. org, 610 434-7811, and at the door