▁verse ▁in ▁Mal ay al am ▁poetry , ▁by ▁writing ▁po ems ▁without ▁following ▁po etic ▁rules , ▁met re , ▁or ▁rh yth ms . ▁Id im uz h ak k am , ▁Minn al V el ich am , ▁Ch ak ra val ath in ap ur am , ▁Rand u ▁Maz ha ▁Ve en alo ▁and ▁A ark k ari yan am ▁were ▁written ▁in ▁free ▁verse . ▁In ▁late ▁ 1 9 6 0 ' s , ▁he ▁shift ed ▁his ▁attention ▁to ▁Ker ala ▁history ▁and ▁its ▁links ▁to ▁Sang am ▁literature ▁and ▁published ▁his ▁first ▁book ▁on ▁Ker ala ▁history , ▁ ▁Ker al ath ile ▁St al ach ar it r ang al , ▁in ▁ 1 9 6 9 . ▁Later , ▁he ▁further ed ▁his ▁research ▁with ▁assistance ▁from ▁Ker ala ▁Sah ity a ▁Akadem i , ▁and ▁published ▁four ▁books ▁on ▁to pon ym y ▁viz . ▁Ker al ath ile ▁St al ach ar it r ang al : ▁Th r iss ur , ▁Ker al ath ile ▁St al ach ar it r ang al : ▁Er nak ul am , ▁Ker al ath ile ▁St al ach ar it r ang al : ▁Pal ak k ad ▁and ▁Ker al ath ile ▁St al ach ar it r ang al : ▁T riv and rum . ▁His ▁work , ▁R ig ved ath il ude , ▁is ▁an ▁attempt ▁to ▁relate ▁the ▁R ig ved a ▁to ▁the ▁history ▁of