Here are my recommendations of books that I've found helpful to work on improving Spanish grammar, vocabulary, etc.
I LOVE this book as a review of all the irregular and tricky rules in Spanish. It's nice if you are learning Spanish to have this book, so you can better understand confusing aspects of Spanish and times when things seem to be breaking the rules. If ...
Correct Your Spanish Blunders: How to Avoid 99% of the Common Mistakes Made by Learners of Spanish
It's another book that focuses on the nuances and exceptions to the rules that a lot of textbooks and other language learning programs may not cover. It's great for intermediate or advanced Spanish speakers to work aspects of the language that are a ...
1001 Pitfalls in Spanish, 4th Edition
This book is more academic and in-depth than “Correct Your Spanish Blunders” and “1,001 Pitfalls in Spanish” in explaining the reasons behind different quirks of Spanish. If you just want a review of the tricky Spanish rules, those two books are grea...
¿Por qué? 101 Questions about Spanish
This book is for advanced Spanish speakers to be able to identify areas to improve their Spanish by practicing different Spanish-to-English and English-to-Spanish translation exercises. I find these types of activities to be really helpful because in...
En otras palabras: Perfeccionamiento del español por medio de la traducción, 3rd edition
It's a little book with 250 idioms and phrases. I find it to be well-organized and easy to read and understand.
Merriam-Webster's Easy Learning Spanish Idioms
If you are looking to add (or understand) more Spanish expressions and phrases, this dictionary has a nice collection! There are 1,200+ Latin American Spanish phrases and expressions with an English definition or equivalent. Then, there are 700+ Engl...
Dictionary of Latin American Spanish Phrases and Expressions