Prime graph components of finite simple groups

Let $G$ be a finite group and $\pi(G)$ the set of prime factors of its order. The prime graph of $G$ is the graph with vertex-set $\pi(G)$, two vertices $p$ and $q$ being joined by an edge whenever $G$ contains an element of order $pq$. This article contains an explicit description of the primes in each of the connected components of the prime graphs of the finite simple groups of Lie type of even characteristic. This solves question 9.16 of the “Kourovka Notebook”.
Bibliography: 15 titles.