The rules that Hardy and Littlewood adopted for their collaboration were spelled out by Harald Bohr in a lecture which he gave in 1947 (see for example where there is also an interesting discussion as to how far they stuck to their own rules and how far they ignored them):
Ang patakaran na Hardy at Littlewood pinagtibay para sa kanilang pakikipagtulungan ay nabaybay out by Harald Bohr sa isang panayam na ibinigay niya sa 1947 (tingnan ang halimbawa kung saan ay mayroon ding isang interesante diskusyon sa kung gaano kalayo sila nananatili sa kanilang sariling mga patakaran at kung gaano kalayo sila pinansin ang mga ito):