APA

Shigo A. L., . (1989). A new tree biology : facts, photos, and philosophies on trees and their problems and proper care. Durham, New Hampshire: Shigo and Trees, Associates.

Chicago

Shigo Alex L, . 1989. A new tree biology : facts, photos, and philosophies on trees and their problems and proper care. Durham, New Hampshire: Shigo and Trees, Associates.

Harvard

Shigo A. L., . (1989). A new tree biology : facts, photos, and philosophies on trees and their problems and proper care. Durham, New Hampshire: Shigo and Trees, Associates.

MLA

Shigo Alex L, . A new tree biology : facts, photos, and philosophies on trees and their problems and proper care. Durham, New Hampshire: Shigo and Trees, Associates. 1989.