### How can i know if a field is monigenic?

I know the next field is monogenic but sagameth doesn't give me a power basis.

c=sqrt(-(5+2*sqrt(5)))
L.<c>=QQ[c]
OL=L.maximal_order()
B=OL.basis()
L;OL;B;L.integral_basis()

Number Field in a with defining polynomial x^4 + 10*x^2 + 5 with a = 0.?e-18 + 3.077683537175254?*I
Maximal Order in Number Field in a with defining polynomial x^4 + 10*x^2 + 5 with a = 0.?e-18 + 3.077683537175254?*I
[3/8*a^3 + 3/8*a^2 + 1/8*a + 1/8, 3/4*a^3 + 1/4*a, 1/2*a^3 + 1/2*a^2, a^3]
[3/8*a^3 + 3/8*a^2 + 1/8*a + 1/8, 3/4*a^3 + 1/4*a, 1/2*a^3 + 1/2*a^2, a^3]