I’m not of the opinion that books can provide a holistic approach to learning Spanish (or any other language for that matter).
The books recommended here are great for supplemental study. They go over (adult) basics like grammar and sentence structure, which I feel are important. Even if you’re using a software program that takes a “natural” non-grammar approach to learning Spanish, it’s still good to supplement with some extra information.
These books will also talk about ‘tricks’ you can use to ramp up tu comprensión de los palabras de Español [your comprehension of Spanish words].