1.7.1.1. Video: How to read the International Phonetic Alphabet - YouTube - https://www.youtube.com/watch?v=MZsAkySZwwU

1.7.1.2. Video: The TH Sound in English - New and IMPROVED Lesson - YouTube - https://www.youtube.com/watch?v=CYWV4ISaBNM

1.7.1.3. Article: the analysis of english education students' difficulties in pronouncing ... - https://www.researchgate.net/publication/381062737_THE_ANALYSIS_OF_ENGLISH_EDUCATION_STUDENTS%27_DIFFICULTIES_IN_PRONOUNCING_ENGLISH_VOWELS

1.7.1.4. Article: Instruction Matters: Spelling of Vowels by Children in England and ... - https://pmc.ncbi.nlm.nih.gov/articles/PMC3607663/