olemus
ISO/IEC/IEEE 24765:
kasutaja määraline rahulolu pragmaatiliste eesmärkide saavutamisega, sealhulgas kasutamise tulemuste ja tagajärgedega
= degree to which a user is satisfied with perceived achievement of pragmatic goals, including the results of use and the consequences of use

ülevaateid
https://jesusgilhernandez.com/2016/10/08/usefulness-usability-and-desirability/
https://www.quora.com/What-is-the-difference-between-useful-and-usable
https://www.interaction-design.org/literature/article/usefulness-the-usability-foundations?srsltid=AfmBOoqPwVr2I4i7Ayx4aTa0hJpAg76yVWewS6WFdD0oItG69arF1GpZ
https://www.researchgate.net/publication/200085965_Perceived_Usefulness_Perceived_Ease_of_Use_and_User_Acceptance_of_Information_Technology