Quadratic subfield of cyclotomic field
53701
Unique quadratic subfield of $\mathbb{Q}(\zeta_p)$ is $\mathbb{Q}(\sqrt{p})$ if $p \equiv 1$ $(4)$, and $\mathbb{Q}(\sqrt{-p})$ if $p \equiv 3$ $(4)$
117789
Computing Galois Group of $\mathbb{Q}(\sqrt{2},\sqrt{3}):\mathbb{Q}$
134619
Galois extension with $X^4-2aX^2+b\in\mathbb Q[X]$
155125
Every ordered field has a subfield isomorphic to $\mathbb Q$?
125568
Construction of $p^n$ field
49150
Subscript R notation for the finite fields
154318
Can a field be isomorphic to its subfield?
153444
$\mathbb{Q}(\sqrt[3]{2})$ is not in any cyclotomic extension of $\mathbb{Q}$
136770
Any field that contains the integers contains the rationals as a subfield (Analysis proof)
60816
Irreducibility of special cyclotomic polynomial.
73412
Splitting field of $x^6+x^3+1$ over $\mathbb{Q}$
112909
is a number field by definition a subfield of $ \mathbb C $?
150170
Subrings of fraction fields
9520
Subfields of $\Bbb Q(\zeta_8)$
147585
Tensor Product of the fraction field of the Gaussian Integers
119832
Galois group of the splitting field of the polynomial $x^5 - 2$ over $\mathbb Q$
68635
When is $2$ a quadratic residue mod $p$?