There are several books available on "Larsen's Opening" on Amazon, including one by well known Grandmaster Andy Soltis "Larsen's Opening 1 P-QN3" , written in 1972, and another "Larsen's Opening", written in 1986, from Bill Wall, who is well known chess author and is also a member here.
Three posts on his blog here may be helpful:
Does anyone have any links to where I can buy a book or research about the opening b3 (as white) or b6 (as black) against anything? I tend to play 1.b3 2.e3 3.Bb2 (and the equivalent for black) against any opening and i love it and want to learn more about it. I researched that its called the Larsen's opening or Queens Fianchetto but all I can find are specific variations of it and mainly as white. Any help would be greatly appreciated :)