The authors found research from the field of psychology that conceptualises the types of knowledge or memory needed: declarative knowledge, ie explicit knowledge, knowledge you can state procedural knowledge, ie tacit knowledge you know how to do something but cannot readily articulate this knowledge Another classification identified by the authors is organisational knowledge: formal codified knowledge, such as data and written procedures informal knowledge, such as that embedded in systems and procedures tacit knowledge arising from the capabilities of people cultural knowledge relating to customs, values and relationships