A new book by Daniel Freeman entitled Josef Myslivecek, "Il Boemo": The Man and His Music was just released in 2009 - published by 'Harmonie Park Press' out of Michigan; $38 on Amazon at the moment w/o a discount (and of course no 'used' copies yet!) - will eventually try to borrow this book or obtain a 'cheaper' option. 

Well, I was able to obtain a library loan of the book above, which is divided into 4 major parts:
Part 1 -
A Biography of Josef Myslivecek (first 100 pages or so)
Part 2 -
The Music of Josef Myslivecek (the next 110 pages)
Part 3 -
Myslivecek and Mozart (about 30 pages)
Part 4 -
Catalogs of Myslivecek's Instrumental and Vocal Music (about 120 pages)
I concentrated mainly on Parts 1 & 3, and scanned through the catalogs - below is just a summary of his mainly instrumental compositions (of course, not listed are those considered 'dubious', lost, etc.):
Instrumental Works:Symphonies - 55
Dramatic Overtures - 29
Solo Concertos - 14 (Violin, 10; Cello, 1; Flute, 1; Keyboard, 2)
Duo Concertos - 3 (2 clarinets & 2 horns)
Wind Ensemble - 9 (Octets, 3; Quintets, 6)
Chamber, Misc. - 6 (Oboe Quintets)
String Quintets - 12 (2 sets of 6)
String Quartets - 23
String Trios - 27 (also 6 cello duets w/ bass)
Flute Trios - 6 (w/ violin & bass)
Flute Duets - 6 (w/ bass)
Violin Sonatas - 23 (w/ bass or keyboard)
Keyboard Sonatas - 13
Vocal Works - 26, Operas; Oratorios, 8; Cantatas, 14; Masses, 7; and much more!
Amazingly prolific and likely the most important musical influence on the
young Mozart (more than Leopold, possibly?) - of course, little of this huge output is recorded -
