Alot of the covers for these are confusing as hell. Doctors Orders had McCoy in his TV show shirt.
Time for Yesterday has Spock in a Blue Wrath of Kahn movie jacket- ive only seen red ones.
Adobe of Life they had movie outfits on
Black Fire is post series i think because they talk about refitting the bridge with all new GREY consoles instead of the colored ones.
The TOS books even sometimes show TOS outfits and the movie starship Enterprise refit, or some other goofy combination. They used to confused me so much because of the covers as a child.
For a while there in the 80s some people assumed there was a second five year mission, before
TMP. So you've got some variously interpreted combinations of when the uniforms changed and when the Enterprise was refit. Although even by that logic is seems stupid to have a refit Enterprise with TOS uniforms. The Enterprise obviously changed appearance during the refit that ended at the start of TMP.
A second 5 year mission between TOS and TMP would actually make alot of sense. The characters appearances would change at a rate closer to that of the actors, and all those 5 year mission stories would have 10 years to take place over. And not much happened in the decade between TMP and TWOK, the decade which would be cut in half by that chronology. Alas the makers of the Star Trek Chronology had to interpret everything strictly by the info in the shows/films. And now we are stuck with it forever.