An article in English in which Imam Ibn Rajab Al-Hanbaly shows the virtues of fasting in Summer, with mentioning the proofs from the Quran, Prophetic tradition, and Companions' sayings about the virtues of fasting.
This article in French shows that fasting the six days after Ramadan is an evidence on the fasting person's thanks to his Lord almighty for His easiness of fasting Ramadan, increase in goodness. It is also a sign of loving the righteous deeds and a desire to continue in this righteous path.