IS THIS A REAL SPANISH TENSE?

Hola amigos Can anyone tell me if the following three sentences employ a valid Spanish construction. He estado leyendo muchos libros interesantes. Mi hermano ha estado comprando demasiada ropa. Hemos estado buscando nuestro diccionario. I have not been able to find any mention of these compound tenses in any of my grammar books, so I am wondering if they are just a figment of my imagination. Maybe they are examples of too literal a translation of the English construction. Thanks in advance to anyone who can help.

I am sure they exist. They just aren't used much. They are the past perfect progressive. More often just expressed in the presente de indicativo or imperfecto. estoy leyendo o estaba leyendo. see this http://spanish.about.com/od/verbtenses/a/compound-past-tenses.htm