@testset "5.2 Inverse cosine" begin
    include("5.2.2 (d x)^m (a+b arccos(c x))^n.jl")
    include("5.2.4 (f x)^m (d+e x^2)^p (a+b arccos(c x))^n.jl")
    include("5.2.5 Inverse cosine functions.jl")
end
