@book { ConstructivistOrientedLessons,
    title = "Constructivist Oriented Lessons",
    subtitle = "The Learning Environments and the Teaching Sequences",
    author = "Ari {Widodo}",
    year = "2004",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1098136"
}