Source: https://www.researchgate.net/publication/324182879_IMPROVING_STUDENTS'_SPEAKING_SKILL_THROUGH_GUESSING_GAME_TECHNIQUE_AT_GRADE_X-I_OF_SMA_NEGERI_1_ANGKOLA_SELATAN_TAPANULI_SELATAN/fulltext/5ac595e6a6fdcc051daf2cf2/IMPROVING-STUDENTS-SPEAKING-SKILL-THROUGH-GUESSING-GAME-TECHNIQUE-AT-GRADE-X-I-OF-SMA-NEGERI-1-ANGKOLA-SELATAN-TAPANULI-SELATAN.pdf