Icon indicating creativity: "Creativity" by Becris at Flaticon, licensed under CC BY 3.0
Icon indicating grammar: "Grammar" by gnak at openclipart, file size reduced. Licensed under CC0 1.0.
Icons indicating activity types: iconmonstr, no attribution required.
Unidad 1 title banner image: "Map of Hispanophone World" by Onofre_Bouvila, cropped, framed and, on unit pages, desaturated. Public domain.
Unidad 2 title banner image: “A Day in Old San Juan, Puerto Rico”, cropped and desaturated on unit pages. Licensed under CC BY 2.0
Unidad 3 title banner image: "Downtown Reading PA" by Smallbones, cropped and desaturated on unit pages. LIcensed under CC0 1.0
Unidad 4 title banner image: Untitled image located at https://pixabay.com/photo-2944064, by Geralt, cropped and desaturated on unit pages. Licensed under CC0 1.0.
Unidad 4, "El intercambio colombino: Productos agrícolas importantes" by Janice E. Rodríguez contains images from Pixabay, licensed under CC0 1.0.
Other images are attributed in their captions.