It helps me to make a relation entity model with barker notation of the following problem. A zoo needs a computer application to keep track of its organization regarding the species it owns, the employees (keepers and guides), and the different visit itineraries it offers. The information is structured as follows: Species: of the species it is interesting to know the name in Spanish, the scientific name and a general description. It must be taken into account that a species can live in different natural habitats and that a habitat can be occupied by different species. The species are found in different areas of the park so that each species is in one area and there are several species in one area. Habitats: the different natural habitats are defined by the predominant name, climate and type of vegetation, as well as the continent or continents in which they are found. Zones: the zones of the park where the different species are found are defined by the name and the extension they occupy. Itineraries: the itineraries run through different areas of the park. The information of interest for the itineraries is: itinerary code, the duration of the route, the length of the itinerary, the maximum number of authorized visitors and the number of different species that it visits. It must be taken into account that an itinerary runs through different areas of the park and that an area can be covered by different itineraries. Guides: park guides are defined by name, address, telephone number and date when they started working at the zoo. It is interesting to know which guides carry which itineraries, taking into account that a guide can take several itineraries and that an itinerary can be assigned to different guides at different times, these being a piece of information of interest. Caregivers: Caregivers are defined by name, address, telephone number and date of entry into the park. It must be taken into account that a keeper can be in charge of several species and that a species can be cared for by several keepers, the date on which a keeper takes charge of a species is of interest