1. Pea Ridge: Civil War Campaign in the West by William L. Shea and Earl J. Hess (1992).
The 1990s comprised a golden decade for authors, publishers, and readers. Entire aisles at mega bookstores like Barnes & Noble and Borders were crammed with Civil War titles of all kinds (the contrast to B&N today is rather disheartening given that the actual richness of the literature is not at all diminished). One of the best titles released during this era was Shea and Hess's Pea Ridge, a treatment of the campaign that's unrivaled in every way to this day and perhaps may never be superseded.
If detailed, full-length battle studies aren't your thing, then Knight's popular overview (which, if I recall correctly from the notes, heavily references Shea & Hess) will more than suffice.
Part of Nebraska's This Hallowed Ground series, this volume is the best guide for touring the Pea Ridge battlefield. Including the critical Ozarks thoroughfare of the Wire Road in the book was an inspired choice.
This highly readable government report is an archaeological study of the battlefield that arrives at some interesting conclusions. You can download the digital version for free from here.
by Robert G. Schultz (2014).
The resounding victory at Pea Ridge left Union military authorities in NW Arkansas in a quandary over how to properly exploit it. While its narrative is choppy and maps poor, Schultz's book is the first and only full-length account of General Curtis's long march west to east across the state and his occupation of Helena after the aborted advance on Little Rock.