Mary Peters married her mentor in 1932, and their scientific collaboration continued until Louis Fieser's death in 1977.  Their early research together focused on the chemistry of quinones  and steroids ,  and they developed syntheses of Vitamin K , cortisone , and the antimalarial compound lapinone .  However the Fiesers were best known for their numerous books. Their first joint textbook, Organic Chemistry (1944),   became very successful and influential on both sides of the Atlantic because of the originality in the presentation of the material, and went through many editions. In 1967 the Fiesers began to publish Reagents for Organic Synthesis and produced six volumes before Louis Fieser's death:  Mary continued the project with collaborators.  They also published a Style Guide for Chemists in 1959,  as well as a seminal monograph on Steroids the same year. 
Steroids are known to undergo color and fluorescence reactions in concentrated sulfuric acid. The fluorescence was correlated in many cases to the development of an uv absorption at 460–490 nm, generated by steroidal 4-en-3-ones and 4,6-dien-3-ones. The potassium salt of a 4,6-dien-3-one, namely aldadienic acid ( 2 ), was selected as a model compound because of its strong fluorescence and uv maximum at 484 nm in H 2 SO 4 . The fluorescent product could be isolated in a 77% yield, to which the structure of a 17β-methyl-18-nor-4,6,8(14)-trien-3-one ( 3 ) was assigned. The rate limiting step was the formation of a C-17 carbonium ion, which was stabilized by migration of the C-18 methyl to C-17 and by proton abstraction from C-14. The generated double bond in 13–14 shifted to the conjugated 8–14 position. 6-Dehydro-17α-methyl-testosterone ( 6 ) followed the same reaction to the trienone 7 . The reaction can be applied to steroidal 17α-alkyl-17β-hydroxy-4,6-dien-3-ones and to 17α-alkyl-17β-hydroxy-4-en-3-ones with substituents in C-6,7, which introduce a double bond upon acid treatment ( . OH).