From my lecture notes of topological quantum field theory we expanded the holonomy
$H_{\gamma}(A)=\lim_{N\rightarrow\infty}e^{iA_{\mu}(x_1)dx_1^{\mu}}...e^{iA_{\nu}(x_{N-1})dx^{\nu}_{N-1}}$
in power expansion of A obtaining
$H_{\gamma}(A)=1+i\int_0^1dsA(s)+i^2\int_0^1ds\int_0^sdtA(t)A(s)+...$
where
$A(s):=A_{\mu}(x(s))\frac{dx^{\mu}(s)}{ds}$
It is not clear to me how is this expansion made. Where could I find some informations about it?
EDIT
There's what I pointed out.
We can expand the first expression to:
$H_{\gamma}(A)=\lim_{N\rightarrow\infty}(1+\sum_{i=1}^{N-1}iA_{\mu_i}(x_i)dx_i^{\mu_i}+i^2\sum_{i=1}^{N-1}\sum_{j=1}^idx_i^{\mu_i}dx_j^{\mu_j}A_{\mu_i}(x_i)A_{\mu_j}(x_j)+...)$
Then, by changing of variable with support [0,1] and using $A(s)$ defined above, we can do a continuum limit obtaining the integrals and so the expression I wanted to prove.
Do you think that this procedure is right?