Ossature en acierlien=//upload.wikimedia.org/wikipedia/commons/thumb/2/2e/Lloyds_Axe_and_Willis.jpg/170px-Lloyds_Axe_and_Willis.jpg|vignette|200px|Ossature en acier rectangulaire, ou «charpente périmétrique» du bâtiment Willis (à droite) contrastain avec la charpente du 30 St Mary Axe, à Londres. L'ossature en acier est une technique de construction avec une ossature de colonnes verticales en acier et de horizontales, construites selon une grille rectangulaire pour supporter les planchers, le toit et les murs d'un bâtiment qui sont tous attachés à l'ossature.
Tertiary sourceA tertiary source is an index or textual consolidation of already published primary and secondary sources that does not provide additional interpretations or analysis of the sources. Some tertiary sources can be used as an aid to find key (seminal) sources, key terms, general common knowledge and established mainstream science on a topic. The exact definition of tertiary varies by academic field. Academic research standards generally do not accept tertiary sources such as encyclopedias as citations, although survey articles are frequently cited rather than the original publication.
