The two used their talents and Berta's connections to prepare children's sections for "Good Housekeeping", "McCall's", "Pictorial Review", "Asia", "Century", and "The Christian Science Monitor". They did pictures and cut-outs, often featuring children dressed in national costumes. In "Berta and Elmer Hader's Picture Book of Mother Goose", the couple collated pen-and-ink and color drawings they had done for "Monitor" and "Good Housekeeping" to great acclaim. When the US Postal Service dis-allowed the sending of magazines with cut-out segments in 1926, the Haders switched gears, gaining a contract with MacMillan for a series of children's books. They began writing the stories for some of the books in this period. Demand for their product soared, and they worked incessantly from 1927–1931, illustrating, in some cases writing, producing, and helping to sell thirty-four titles. They stayed busy for the rest of their lives, producing another seventy or so books before they retired in 1964. One book in particular, "Billy Butter" (1936), so impressed writer John Steinbeck that he requested Elmer Hader do the cover to "The Grapes of Wrath" (1939). Hader eventually did covers for two other Steinbeck works, "East of Eden" (1952) and "The Winter of Our Discontent" (1961).