Lebih baik sekarang daripada nanti: pengaruh waktu pemberian umpan balik dari penerima surat terima kasih terhadap kebahagiaan pengirim = Better now than later: the effect of delayed feedback from receiver of gratitude letter towards sender's happiness

The conquest of happiness

Stability of happiness : theories and evidence on whether happiness can change

Kebahagiaan yang membebaskan : menghidupkan lentera di dalam diri

All you wanted to know about happiness/ Vikas Malkani