Hi Halina, Sri Mimosa here...
OK, padas...K.N. Rao mentions them in his book on Jaimini's Chara Dasha. Here's how you compute them...
Let's start with A4, or 4th House significations...
The 4th House from lagna Libra is Capricorn. Saturn rules Capricorn. Saturn is in Aries. Starting from Capricorn, count how many houses there are until you come to Aries. So Capricorn, Aquarius, Pisces, Aries. There are 4 houses. Now, starting from Saturn in Aries, count 4 houses. So Aries, Taurus, Gemini, Cancer. So Cancer is the sign which gets the A4.
Same thing with A6, or 6th House significations...
The 6th House from lagna Libra is Pisces. Jupiter rules Pisces. Jupiter is in Taurus. Starting from Pisces, count how many houses there are until you come to Taurus. So Pisces, Aries, Taurus. There are 3 houses. Now, starting from Jupiter in Taurus, count 3 houses. So Taurus, Gemini, Cancer. So Cancer is the sign which gets the A6.
Do the same with A8, or 8th House significations...