These are several books that I have used throughout the past couple of years that have helped me:
Tonal Harmony by Stefan Kostka and Dorothy Payne - this book gives a lot of information about voice leading, chord analysis, part-writing, etc. Though this book has been very helpful for me there are some flaws with it. While many of the music examples are helpful, some are not. Also, some of the wording of the text is confusing and only seems to complicate things, but a majority of it is very informative and has helped me considerably when composing.
Hearing and Writing Music by Ron Gorow - Though this book primarily focuses on ear training, I have found it to be an excellent resource for writing for instruments I am not too familiar with. It has a section dedicated to talking about the different instrument groups, how to write for them, their ranges, and how to notate the different ways of playing them.
I have also heard that Understand Post-Tonal Music by Miguel Roig-Francoli and Music Composition by Reginald Smith Brindle are also very helpful books, however I have not read through them personally.
I hope this has helped, and have fun composing!