Indefinite and definite articles

Spanish Proficiency Exercises (Use of articles): https://www.laits.utexas.edu/spe/int15.html?v=g
Los artículos: https://debocaenbocacentro.wordpress.com/2015/01/16/los-articulos-parte-i/
Spanish Grammar in Context (Definite articles): http://grammar.spanishintexas.org/determiners/definite-articles/
Spanish Grammar in Context (Indefinite articles):http://grammar.spanishintexas.org/determiners/indefinite-articles/

Los artículos determinados e indeterminados: https://www.youtube.com/watch?v=fChEjou2O4g
Indefinite and definite articles. Level A1: https://www.youtube.com/watch?v=mZPjk2fb0L4&t=42s
60- Second Spanish Grammar: Nouns-Indefinite articles via the LEAF Project: https://www.youtube.com/watch?v=nwMVXafUxcc
60- Second Spanish Grammar: Nouns-Definite articles via the LEAF Project:https://www.youtube.com/watch?v=g9qQE2Bp8os