Symplectic Geometry
《Symplectic Geometry》 · 第 56–58 页 · Section 3.4，半扭转符号约定与 Figure 3.8(b)，令 q=2
A sequence of half-twists in a diagram can be replaced by a box containing an integer: the sign of the integer indicates the sense of the twist as shown in Figure 3.7. […] When \(q=2\), the knot in family (b) is called a twist knot.