Nostalgia by DETLEFSEN and Autumn Reflections by SHUMAKER

Just found these behind some 8 X 10 photos my grandmother had covered them with. Oh my gosh!
Nostalgia is NO. 369 International Gallery Prints
Autumn Reflections is NO. 309 International Gallery Prints
bottom of print LEFT hand side states
D.A.C. N.Y. NO. 309 PUBLISHED FOR WINDE ASSOCIATES INC., N.Y. N.Y.
bottom of print RIGHT hand side states
LITHO IN U
Any information on these and their timeline would be wonderful!