 wrote down seven mock theta functions of order 6 in his lost notebook, and stated 11 identities between them, which were proved in .Two of Ramanujan's identities relate φ and ψ at various arguments, four of them express φ and ψ in terms of Appell–Lerch series, and the last five identities express 
the remaining five sixth-order mock theta functions in terms of φ and ψ. discovered two more sixth order functions.The order 6 mock theta functions are