[1] Boman J.: 
Differentiability of a function and of its composition with a function of one variable. Math. Scand. 20 (1967), 249-268. 
MR 0237728[2] Debecki J.: 
Natural transformations of affinors into functions and affinors. Suppl. Rend. Circ. Mat. Palermo II 30 (1993), 101-112. 
MR 1246624 | 
Zbl 0816.58002[3] Debecki J.: 
Natural transformations of affinors into linear forms. Suppl. Rend. Circ. Mat. Palermo II 32 (1993), 49-59. 
MR 1283621[4] Kolář I., Michor P. W., Slovák J.: 
Natural Operations in Differential Geometry. Springer- Verlag, Berlin, Heidelberg, 1993. 
MR 1202431[5] Krupka D.: 
Elementary theory of differential invariants. Arch. Math. 14 (1978), 207-214. 
MR 0512763 | 
Zbl 0428.58002[6] Mikulski W.: 
The linear natural operators transforming affinors to tensor fields of type (0,p) on Weil bundles. to appear. 
MR 1885318 | 
Zbl 1029.58001