1. https://www.chegg.com/homework-help/questions-and-answers/exercise-1-consider-graph-twelve-vertices-nine-vertices-degree-3-one-vertex-degree-two-ver-q32927477
2. https://www.chegg.com/homework-help/questions-and-answers/exercise-2-let-n-positive-integer-construct-connected-graph-2n-vertices-exactly-two-vertic-q32927493
3. https://www.chegg.com/homework-help/questions-and-answers/exercise-3-let-g-connected-graph-vertex-set-v-distance-two-vertices-u-v-denoted-dist-u-v-d-q32927502